what is the best way to make normal maps for a low poly model?

By making a high poly model and projecting the normals onto the low poly.

http://www.youtube.com/watch?v=ybiHIUWPZnc

Really simple but goes over what it is
Edited by Higuy on Feb 18, 2014 at 04:35 PM

is there another way

Well, you could get the unwrap and hand paint it in photoshop/gimp/whatever, but honestly if you want good, clean normal maps, bake them out.

You could use Ndo2 for Photoshop though and create it yourself by mimicking details in the diffuse, or you could use a program like Crazybump to convert the diffuse into a normal. Theres also an nvidia normal map plugin for photoshop but I personally would not recommend using that if you want clean normals.

I honestly do though recommend learning how to bake them out, you will get very good results! :) That is of course that you make a high poly too.

you asked for the best way, but you could do as halo 1-3 and manually paint the normals. however, doing so would produce barely passable results.