I've read videos and books on drapery drawing including the 7 folds etc, but I've serious issues painting them.
Below are some of my work which I did recently. In particular, I'm having the most difficulty with those zig-zag types of folds.
I'll be doing a couple of drapery paintings from photos weekly and need a mentor to tell me what's wrong, what to improve on, what to look out, which area to focus on etc.
In below paintings, I use the photos for reference (didn't try to copy exactly) and use my own main light source.
I also construct the body of the figure out before drawing the drapery on top but erased them out in final drawing.