NEW UPDATE:
Im putting this up due to the volume of people asking for shortcuts.
Quick [tip]when working in a perspective view, Max will likely freeze/crash, the zoon button will break, and you will repeatedly get weird, fish eye lens views!!!I advise switching to a user view, it usually sorts out this problem.[/tip] for you.
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[color=#BF0000]Modeling:[/color]1. Meshsmooth only the selected faces by un-checking the 'apply to entire mesh' box in the meshsmooth options.
2. If you use Non-uniform scaling (scaling in less than all 3 axes at the same time) on a model it will cause distortion problems when animating, however non-uniform scaling within a sub-object mode will not cause the same problems.
3. When in Edit Poly or Mesh, hitting 1,2,3,4 etc will cycle through the sub-object selections, and when in edit poly hiting 6 will take you out of the subobject mode.
4. Alt+X = See-though or X-Ray mode
5. To rotate around a particular vertex, select your object (or set of sub-objects) lock the selection, choose either

or

from the drop down list, turn on vertex snap and rotate it all by clicking on the vertex you wish as the pivot. (CLICK HERE for a video of the process)
6. When in sub-poly mode, creating your own keyboard shortcuts can save oodles of time. Rather than scrolling up and down looking for "connect" and "target weld". Just assign "ALT-C" and "ALT-W" for example.
7.When modelling things at odd angles, (ie, arms, hands, feet etc) it helps to create an instance of the object, straighten it out and work on that instead.
8. Pressing + and - changes the size of the transform gizmo.
9. A sub-object selection in Edit Poly can be transfered over to another one by holding down Ctrl and clicking another mode button in the modifiy panel selection rollout. This is particularly good for the 'Ring' and 'Loop' commands in edge mode of edit poly.
Alternatively selecting the edges/verts .etc around and area (in effect, selecting a perimeter) and holding Shift whilst clicking a different selection mode will transfer over only the parts within the perimeter of the original selection.
10. The FFD modifier is a good tool for deforming meshes, its can be applied to a single mesh or multiple meshes simultaneously.
11. In later versions of max, hitting Ctrl+Backspace will remove both the edge and the vertex when in edge subobject mode.
12.Holding down CTRL when creating a a sphere, cylinder, teapot, etc. will allow you to rotate as you create. Holdings down CTRL when creating a box, pyramid, plane, etc. will create an object with even length/width.
13. When modeling wrinkles, folds, etc, on a curved surface, instead of moving your row of edges on 1 axis, convert the selection to Vertex (Ctrl + Click Vertex button under the stack) and switch your coordinate system to Local.
Now, moving the slection on the Z axis will move them perpendicularly to the surface.
Alternatively you can use the 'Normal' constraint found in the edit poly modify panel for the same effect although this is only in later versions of max.
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[color=#BF0000]Lighting:[/color]1. Ctrl+L switches of you lights and go back to max default 2 point lighting.
Hitting it again will switch back to your own lights.
2. Pressing '9' above the letters on the keyboard will bring up the advanced lighting window
3. Selecting a light then pressing Ctrl+H lets you drag over the surface of an object to place the highlight.
4. When using a target light, selecting the line inbetween the light and its target will enable you to move/rotate both objects together.
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[color=#FF0000]Texturing / Materials:[/color]1. To remove an assigned material from a mesh, drag the NONE material from the 'Material/Map Browser' via the 'Material Editor' on to your mesh, or use the UVW Remove utility in the utilities panel (click the 'more' button to open it).
2. To hide the materials in the viewport select 'Object Colour' in the Shaded section at the top of the display tab.
3. You can now (in later versions of max) apply a single UnwrapUVW modifier to multiple meshes simultaneously to allow them all to be unwrapped onto the same texture map a lot easier.
4. If a material is assigned to anything in the scene, small triangles appear in the corners around the material slot in the material editor.
5. Material editor is not the list of all materials in the scene, here is how to list them: Material editor > get material > scene).
6. To display an assigned texture map in the viewport click the 'Show Map in Viewport' button (the blue/white checker cube) in the 'Material Editor'.
7. Click the eyedropper tool next to the material name then click on an object the viewport and it will copy the objects material to the selected sphere.
8. An easier to use alternative to the Morpher material is to create a multi-sub material with the different materials in it then use a Material modifier on the object and animate the material ID over time. This is particularly useful in Mental Ray as that doesnt support the Morpher material.
9. You can rotate the sphere(or custom shape) in the material editor slot by holding down MMB and dragging your mouse. (you can't rotate it if you enlarge the slot window though)
10. When unwrapping uv's using copy and paste is a HUGE time saver.
11. When unwrapping selecting certain chunks and use flatten mapping to get a head start. (instead of using flatten on everything)
12. You can drag and drop images/video right into the viewports from windows explorer to create a new material with that image/video in the diffuse slot. (just use the eyedropper tool

to place it in the material editor)
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Navagation / Viewports:[/color]1. When in camera view you can lock the camera from panning by selecting the camera itself and its target (if applicable) and checking all the position boxes in the Link Info tab in the Heirachy panel.
2. Ctrl+C in perspective viewport adds a camera to the scene and effectively saves the view you have set up in perspective mode.
3. If there are mutliple cameras in the scene "C" will bring up a list to choose from. Alternatively hitting "C" whilst a camera is selected will change the current view to that of the selected camera.
4. ALT+W = Toggle Full Size View.
5. Ctrl+X = Expert (Full screen) Mode.
6. Pressing the Up key in either Camera or Perspective viewport will enable the walkthrough mode, you can then use the cursor keys to navigate (the rest of the controls are in the help files under 'Walkthrough Navigation'
7. 'G' Toggles the maing grid from viewport
8. 'J' Removes annoying selection brackets around your objects.
9. 'I' Pans the viewport to center on the cursor position (handy if you want to draw lines/shapes which are bigger than your viewport and regualr panning cancels the command)
10. Pressing "Z" will center your zoom on the selected object. This is particularly useful when the middle mouse stops zooming in whilst in perspective mode.
11. Shift+Z will undo the last view change without undoing any commands you have performed and Shift+Y will redo the view change.
12. Mousewheel+Alt+Shift = Arc Rotate
13. Mousewheel+Alt+Ctrl = Zoom
14. Holding Ctrl down whist zooming in increases the zoom speed
15. Holding Alt down whist zooming in decreases the zoom speed
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[color=#BF0000]Particles:[/color]1. Use the 'Mesher' compound object to convert your particle system into an editable mesh object.
2. Snapshot also converts particles to mesh, and automatically converts it to an editable mesh whereas Mesher (above) doesnt.
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[color=#BF0000]General Shortcuts:[/color]1. Pressing the letter 'O' turns off the bounding boxes when panning.
2. Pressing X with toggle the transform gizmos on and off
3. Right click a spinner to zero its value
4. Press the 7 above the letters on the keyboard for an in-viewport poly/vertex counter.
5. Hit Ctrl+N in any numeric input field you access the 'Numerical Expression Evaluator', a simple calculator.
6. Right clicking the transform controllers brings up the Transform Type-In window.
7. Right clicking any of the snaps toggles will bring up Grid and Snap Settings.
8. Hitting Q repeatedly toggles through different selection modes.
9. F3=Smooth/Shade view toggle.
10. F4=Wireframe overlay (Show Edges) toggle.
11. both Ctrl+V and Shift-Dragging clones the selected object.
12. W, E & R are the shortcuts for Move, Rotate and Scale respectively.
13. H = Selection Box (Select by List) shortcut
If you have the new selection box (max 2008+) and want the old one do the following...
find your CurrentDefaults.ini
(usually in something like... C:\yourname\yourname\AppData\Local\Autodesk\3dsmax\2009 - 32bit\enu\defaults\MAX
and change :
[Scene Explorer]
SelectByNameUsesSceneExplorer=1
to
[Scene Explorer]
SelectByNameUsesSceneExplorer=0
save ini file and restart max
14. Spacebar = Lock Selection, this can be hit by accident and you will be unable to select/deselect objects so its good to know to deactivate too.
15. Alt+Q enters isolation mode allowing you to temporarily hide all non selected objects and zoom extents selected.
16. F12 will bring up the keyboard input window for the currently selected transform tool allowing precise values to be used.
17. ALT+D toggles the 'Snaps Use Axis Constraints'. With Vertex Snap, lets you quickly align vertices in only one or two dimensions.
18. SHIFT+X toggles the Edge Constraint. With Vertex Snap, allows you to align vertices in one or two dimensions without deforming the edge(s)
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[color=#BF0000]Animations:[/color]1. Ctrl+Alt+Left-Mouse-Drag on the time line will adjust the starting frame.
Ctrl+Alt+Right-Mouse-Drag on the time line will adjust the end frame.
Ctrl+Alt+Hold down the Mouse Wheel on the time line will pan the time line.
2. Starting in Camera View, switch to perspective view, turn on autokey, adjust the view, move the time slider on some frames, select the camera again and press Ctrl+C, the same camera will now animate to the new perspective position.
3. Got stupidly large file sizes that take ages to save and your using biped? Delete the copy collections under copy and paste in the biped menu thing, you might have loads there and they bump the file size up alot.
4. Right clicking the time line and going to Configure-->Show Selection Range will give you a bar under the keys where you can scale, move and even reverse the selected keys
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[color=#BF0000]Rendering:[/color]1. One tip for Backburner would be to remember to use UNC (ie //servername/folder) addresses for your output files, and make sure each PC has access rites to the said path.
2. F9 = Quick Render
3. Do not use numbers (0-9) at the start of your computer name else it wont be detected by backburner.
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[color=#BF0000]Reactor & Dynamics:[/color]1. Model the objects their real size when you make them, eg. Make pool balls, well , pool ball sized, acording to Google : "A cue ball is 4.75 cm in diameter, while pool balls are 5.03 cm". You will get much better results with the physics this way.
2. If things are 'hitting' before they actually touch , adjust your Collision tolerance.
Utilities TAB, > Reactor>World>col. Tolerance.
3. When setting up a ridgid body selection (or any other reactor type) select all your objects to be added FIRST, then create the Set. This saves you having to add indivual ones later
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[color=#BF0000]Miscellaneous:[/color]1. The white MaxScript area in the bottom left of the screen can be used as a quick-access calculator, just type in the sum, press enter and hey presto!
2. Typing, for instance, r40 in a spinner will add 40 to its value (also works with negative values)
3. If keyboard shortcuts aren't working first make sure the Keyboard Shortcut Override toggle

isn't active.
4. Tired of dragging the Right panel up and down all the time? try grabbing the left edge and dragging it out to the left further to expand it.
5. Holding 'Ctrl' whilst panning in teh viewport, zooming or even using the spinners will increase the speed at which they work. Whilst holding 'Alt' will decrease the speed.
6. When in track view, if you find the keys are locked to a particular type i.e. linear and you can't change them via the buttons above, right click on the name of the corresponding track, choose 'assign controller' and choose the new type of keys you want i.e. 'bezier float'
7. Selecting a section of text in the maxscript window and dragging it to a toolbar will automatically create a button for it.
8. If you develop a glitch in Max that doesnt seem to have a fix, try deleting the 3dsmax.ini file (in the max root folder v8 and lower, in the C:\documents and settings folder v9 and above). A new .ini file will be created the next time you start max and revert any customisations back to default settings.
9. When using a target camera, selecting the line inbetween the camera and its target will enable you to move/rotate both objects together.
10. Right clicking whilst half way through a function i.e. dragging and item, spinning a spinner .etc .etc will cancel the changes made. Good if you do something by accident.
Now its over to you lot to fill in the rest with all those handy hints you know....
11. While using the maxscript editor, place the cursor in a word or highlight it, and press F1 and the help file will pop up and go straight to the page covering that topic.
12. You can re-order the rollouts in the modify panel simply by dragging the title bar to where you want it.
13. By using the text primitive & like webdings etc you can get a good start on otherwise hard to model objects using the font and extrude.
14. Saving empty scenes with specific light and/or render settings (or any other settings) and creating shortcuts for these files is a quick way to define presets to launch max with.
15. When using one of the .chm files (User Reference, Tutorials, Maxscript Reference,...), open it with the run command or a shortcut instead of the help menu in max. Then you can use the Windows kbd shortcut ALT+TAB to shift between windows instead of having to minimize/restore it all the time. I find it handy when following a tutorial for example.
16. Converting an editable poly object to an editable mesh then back to and editable poly can resolve some surface glitches such as incorrectly smoothed edges when applying a turbo/meshsmooth modifier.
17. When you use Hold, max saves your scene as maxhold.mx in the autoback folder. Note the .mx extension instead of .max, so you need to set the option to All Files in the open file dialog to see it.
18. 3ds Max has a pop-up message feature for when a certain file is opened. It's found under Customize>Customize User Interface>Menus>Category>Add a Pop-up Note. Expand the option in the list and just drag the item to the list on the right. Useful when you want to leave a copyright sign or just a message.
19. If you minimise max whilst rendering and cant maximise it, hit Ctrl+Alt+Del, go to the applications tab, select max then use the 'Switch to' button to maximise the window.
[color=#000080]Originally posted by Mr. Grotey[/color]
http://www.mgrote.com