I can name a handful of legendary photographers, yet I can only name 1 famous retoucher...
How many famous retouchers can you name?
Consider that. And then consider how important retouching is to photography. Just as important as hair, makeup, and wardrobe if you ask me.
When I need to up my retouching game, here's where I go: RetouchPro
And if you're too lazy to read, watch some youtube rentals in the comfort and privacy of your own home :)
Disclaimer: Not affiliated with Retouch Pro in anyway, although I think I'm a forum member.