What i did when i first started texturing was to get free concrete textures and stuff and rusty metal.

Import them into your master psd file then play with the blending modes and opacity, also paint with the eraser set to soft and low opacity.

The fractal can look too uniform overall. When i get home i will send you one of my textures, the one i used for some of my star wars models is full of these kind of cheats.

Give you somthing to jam off and do better.