Tranguil222, the following is not directed at you, but everybody in general who uses curves.
I
don't consider myself an advanced "curves" user at all, even if I know the basics about it, but I agree, curves is a magnificent tool, but there's only one problem with it; most people "think" they know how to use it.
I've seen too many images in the past that were really messed up by the wrong use of curves, even by people of whom I thought they knew how to use it. To be honest; there are a lot of people who think they know everything about curves, but actually don't know all that much :\
My advice is; if you don't really know what you're dealing with, then only use curves for some basic adjustments or read one of those books like Photoshop artistry 6 or 7 or a book like Professional Photoshop: The Classic Guide to Color Correction.
Knowing how a tool works is one thing, but using it the right way... well that's explained in a very professional way by these true Gurus of Photoshop.
And you know what is so amazing about these Gurus; they know how to use the right tool at the right moment. H&S, Levels, Curves, they all use them. See, that's the point; they don't need
only curves just to be considered an expert
Just my 2 cents though, take it or leave it