first make a background this is what i got So far now get a render you would like to use for a sig and put it on your sig and then click on your render in the layer secetion and go layer-add layer mask-hide all and this is what you should have now and then get a cool tech brush and click on layer mask and start brushin and this is waht you should have (i did this real quick if you take your time you should have something reall good there) rep or cred is apreciated
try the color mesh thingy CTL+U and colorize it see if that makes a difference oh yes and DONT/DO NOT sink him in make shure that his whole body is showing but you know then agian its just a thought