There are a lot of different techniques to make hair! I'm only going to talk about the 2 I know, but feel free to ask questions.

To make hair, there are a few basic concepts to understand:
Hair is made of strands, curly, straight, wavy, or whatever other texture you can think of, this can change your skinning and shading depending on what you are going for! But one thing in common is that they all go one direction, down. The longer the hair is, the more it splits.
With this knowledge, we can break hair into three different groups when shading: the base, the shadows, and the highlights.

The most common style you'll see, especially with older skins, is "waffle hair." It is a simple template that utilizes 3 primary hair divisions.

While it is quick and easy, I think that this style shows up a little flat on a skin, and isn't quite as natural.

Something we can do to fix this is add gravity to the hair, as it goes down, add divisions. Starting with the main group, we have our base!

But these are just 2 lines, you could hardly tell it was hair! But by lightening the color of the shading the further up you go, the more depth you create.

And there we have it! Our division shading is done. The next step is highlights.

Highlights further imply depth, and add a source of light to the skin, making it more dynamic.

Now, feel free to play around! there is always the 2nd layer which you can use, shade more, highlight more, do whatever feels right to you!
I'm not so good with utilizing the 2nd layer to hair, but here is an example!


Of course, these are all stylistic choices, you make skins how you want to!

can anyone help me improve my skills making skins?