Depending on how you want your thumbs to look many TGPs have better luck by polishing up their thumbs in Photoshop (or such), seems smooth high-contrast thumbs have a better click-thru. I notice that some of your thumbs are blurry and amateur-ish looking, although that may be what you're going for on some, since "amateur" looking does of course work at times. Such as:
Good luck.