Quote - drifterlee, from what I've seen in my Textures folder, a bump map looks just like a greyscale of the texture.

 

That's the quick and dirty way of doing it, but can often get you in trouble. For example, if you greyscale a face with makeup, then the makeup will look either raised or lowered. Likewise with tatoos. There is a nice tutorial here about using bumbmaps on 2nd skins to get a realistic look. Often on clothing, you want to raise trim, and lower seems, so you may want to adjust them that way.