I just kinda go ham until it makes sense, and I never ever like the first version and almost always change it. Every skin you make WILL be better than the last if you just work work work until all the shading and coloring match up.
For coloring, you could blotch areas you want certain parts. Like clothes.
Color the shirt part with the base color, like blue, and the pants or whatever bottoms you want, and change the colors until they pair satisfyingly.
Shading is kind of stupid to explain because ALL I do is try shading the standard way but then get lazy and take a dark color and make it around 15% transparent. Then just brush the places you want to be shaded and it makes sense from there. Also, don't be afraid to try and add the outer layer to clothes just to see if it would look cool, you could just get rid of it if you don't like it.
Those are just my tips, and if you ever don't know how to draw something like a rose or a heart or a beanie or even flannel, just google mc skin (insert drawing u wanna draw) and it's bound to exist somewhere.
