Personally I think you should charge more for your art, especially fully rendered because your textures & colors are gorgeous. And maybe add a "+" to the fully rendered fullbody price, since the other rendered prices have it?
I haven't done commissions so I can't speak from experience, but from what I've read/heard, minimum wage is the lowest you should go for the time you put into the commissions. It might be good to go high in prices to begin with, because it might be hard to raise prices later when people have been expecting your old prices.
Maybe consider what kind of people you'd attract with different prices, too? Having lower prices might get people just looking for the best deal (which is common on dA, it seems), and having higher prices that are fairer for you would seem more professional and be more likely to bring commissioners who like your art, and want to support you as an artist. Also consider if you'd rather do many cheap commissions, or a few expensive ones, if they both end up totaling the same amount of money.
Having a lot of followers/watchers helps in getting commissioners as well, because while many might want to, only a smaller fraction might have the money to actually commission you. Popularity means more attention, and there are a lot of people who just haven't discovered your art yet.

I wish you luck! ovo