Hey there. Nice drawing! :D I'm not an expert at drawing folds, and some may not be correct. But what I'd recommend you to do is first study the different kinds of folds, such as diaper, zig-zag, drop, etc. We need to understand how things work before applying them to our drawings. The other aspect, and that's something Antonil just mentioned in the most recent Short at YouTube, is about the tension (T) and compression (C). Identifying these two things will help you a lot in drawing folds from invention. I have basic knowledge of drapery, but considering these two aspects helps me draw more believable clothing. You can check out the longer version about drapery by Antonio on YouTube. It's called "This Video will save you YEARS of drawing frustration" haha. Hope this helps!
