The first thing you have to do is pick a light direction. This will help you place your shadows and highlights. Then, think about the folds of the fabric as 3D shapes and light them as such. I did a quick and dirty render to show you what I mean, I hope it helps :)
Ah, I get it, there's a lot of room for different methods as long as there are clear shadows and highlights! One more thing, for the base shadows, did you use a brush that changed opacity with pressure, or did you use one base shadow color with the same opacity? Regardless, this is great and I really appreciate the feedback, thank you so much!!
Responder a @ lascanerias
I used a brush that changed opacity with pressure. Glad I could help :)

