Getting texture right is the same as getting landscapes right
You gotta do lots of studies, well, not even lots if you do them properly.
Generally, taking what you find yourself lacking at (like say making metal stuff look like metal and fleshy stuff look like fleshy stuff) and making spheres and cubes and generally trying to find as diverse as possible an array of said things (so for metal you get some rusty refs, some shiny armour, some chrome, some matte stuff, etc..).
That said, What GGI has linked has nice video tutorials on such things which should help you along the rocky road of not suckage.
Also watching Conan has pumped me up for some paintage, expect something soon
And it's done, I guess, don't feel like working on it anymore and the desired effect has been accomplished
Tho looking at it now, the lower body could've been a bit darker to better contrast with the flappy parts.