Re: Skintone effect?
This isn't really an effect. That term is overused when people don't understand the style. The soft color grading might have added to what you perceive as an effect, but I can tell you this isn't something like a photoshop or third party filter. Much of this is done bit by bit. Hair, cheeks, legs, clothing can all be adjusted separately in this manner. The backgrounds once again are adjusted separately. It's obvious that much of this is painted, because otherwise there are things that just wouldn't work that way.
Much of the time these kinds of posts get random responses of how you can make this and this broad adjustment, and it gets you somewhere close, but I can tell you anything done to this level was done in detail and whoever did it knew what they were doing. They probably didn't use much in the way of heavy global adjustments. Those make it hard to get even skin color like this. If someone asks me to create such a look, it's not so much about curves and colors right away. It's about getting the right lighting. The color grading has to be subtle. I just go through and figure out what it needs. It can be okay highlights need more magenta/less green or shadows are too red. On the color you work like this, then as you close in you start to fine tune individual colors or objects. The lighting is the other aspect. Look at how the legs, eyes, hair, and arms are accented. It's continuous enough to sell the image to the viewer, yet it would not come out of the camera just like that. You have to understand how to accent these details.
Anyway I'm trying to tell you not to take this in as one thing. You need to create it bit by bit. Figuring out some of the color early on would probably help you visualize it better. If you're going to do this, I suggest you keep those layers at the top of your stack.
This is going to take some amount of skill if you want it to look good. If you do get suckered in by one of the just do this and this posts, you should not expect anything too amazing.