Hello I want to make a transparent shader for the lens of a scope, but I do not know how to approach it. What kind of shader would I need to use? Would the diffuse just be a solid color? Does it need a multi? I don't have much experience with shaders. I have looked at some of the stock tags, but I just want a shove in the right direction.

Well, there's shader_model scopes like the br scope, and transparent scopes like the CMT sniper scope. My suggestion would be to use a shader_model OR shader_transparent_glass.
If your bitmap has an alpha the way you want it, it should be easy. Definitely look at the b30 glass or something.

I know how to do transparency but the one thing about transparent_glass is that no matter how dark your surroundings are, it will always have the same lighting, which will make it stick out in the dark. But I guess that's really not a big deal.

Did you try making a specular mask?

I do not know what that is.