Here are a few tips I picked up on creating normal map textures for games:
For scaling textures: 512 pixels is the height of a person. On an iphone or other low res display this would be smaller.
For Mark Cullens normal map script: Install normal map script to the plugins folder. Make your model and in orthographic view and apply the script as a diffuse material. be sure to switch off customise>preferences>gamma and lut
Make a plane the size of your render area, and then model on top of it. make sure the plane is square shaped. then the render may be slightly larger or smaller than the power of two texture size (512,1024 etc) but can be scaled in photoshop. basically model as high poly as you want, as it will all be converted to texture information later, and the polys wont matter.
because its an orthogrrahic view, objects can be in front or behind of each other and wont be affected by perspective etc. so you can pull an object forward ‘ flip’ modify it, and it will appear to engrave in, rather than stick out of the plane.
Height map- just for dust and rust etc. Normal map should be used to affect the actual chunky geometry look.
Diffuse map has no shadows- the lighting and normal map will be used to generate these in game.
In unity engine create an alpha channel in photoshop- specular maps sit in the alpha channel. Specular map decides whats shiny and whats not on a texture
Normal, specular and diffuse are always used in this generations game textures. You may even have opacity maps etc.
create model as high as you want, apply normal texture. render image. model is no longer needed. just use the rendered texture.
Standard character poly count is 4000-5000 for enemies, grunts. Main characters are about 15,000.
Modelling chairs etc – 150-200 polys. keep it as low as possible.
Shift+f to see rendered area in viewport.