The best way to get better at drawing folds is observation and practice. Try drawing real life people, and observing how clothes fall on them. There was a really great tutorial in one of my How to Draw Manga books, I forget which one though... (I'm sorry!) Things to remember are that folds are almost always directly affected by gravity, but how hard it pulls depends on the stiffness and texture of the material. Light, gossamer material falls in straight folds directly down from the highest point (like, if you have a character standing directly up wearing a gown of thin, loose material, the folds will fall directly down from the shoulders or any points that stick out more, like hips or chest areas). But stiffer material, like jeans, tends to stick up a bit on its own, you know what I mean? Hopefully I'm making sense and not feeding you wrong information... Like I said, observation is the best. It doesn't even mean you have to observe real life, look at professionals drawings and see how they draw them. And keep working on it!