High-End Retouching Techniques?

I should have been more specific in my post. This thread was only meant to refer to high-end portrait retouching. When I say I am "getting into" high-end retouching I mean that is now becoming my main focus as an amateur photographer. I would assume that most retouchers are using Photoshop.

I am not worried about business practices or client issues; I was just curious what were the basic high-end photoshop techniques.