This sounds like excellent advise. I like your thinking Harlan. Since I dont paint on a regular basis, I can say regarding creating a thing someone gave me this advise that seems to stick with me very well and it is simply, "Once you have it, COMMIT to your design" which has helped me a lot. I dont know if this applies
to this question but though it was of value to mention???
Welcome to the forums, Rossana!!!
Could you be a bit more specific about what your difficulty with the folds in the fabric is? A very good rule for oil painters is to stop painting what you "know" is there, and paint what you see. If you try to paint a gold ring thinking about it being a gold ring, it becomes a difficult project. If you stop thinking about it being a gold ring and just look to see what is really there, the different colors and the shading, the task becomes simpler. Maybe that would help with your fabric problem?
Posting a photo of your project may help us figure out what the problem is and give you more useful advice.