Practice practice practice. Its been about 1 year and 3 months since the first time I ever used photoshop and 3dsmax. Pretty much at least an hour a day of that year and a bit was spent playing with photoshop. I didn't use tutorials or anything like that. They can help but nothing is a substitute for practice.

Also it should be noted. Anyone that downloaded the Spartans. I have updated the downloads with fixes to the model which included a seam and a mapping error on the cloak. I suggest re-downloading the files.