well to start with im a pencil/sketch artist, so using a wacom tablet makes my textures a LOT easier, dodge and burn on a 50% gray pallet is a good tool, then making some color layers, making selections, playing with the modifiers under the selection tabs, and right click on a layer, go to blending options, play with those effects, you’ll get some good looking stuff, oh and heres a simple example on the texturing process, as quoted from another post i made on another thread:
“Height Map”

“Normal Map”

how to make a height map in photoshop is to understand what the highest extrusion on you bump is going to be, the normal, cause in this technique you cant make anything higher than white. white is your normal area, the standard blue, grays and black are lowered bevels.
after making a height map, you can render height to normals, normals to cavity which looks like this VV

Cavity maps are good for overlaying detail into a diffuse, it can add depth to a flat texture.
and of course with a height map you can render an ambient occlusion map as seen below VV

and thats a minor tutorial on the texturing process following the creation of a diffuse, cause otherwise youll get low quality grain, which may be good but on a lower level and using a detail map. 
to make what ive made easier, download Xnormal, its free and not only is it a program, itll plugin to your filter’s tab in photoshop for easy use, play with it.