How to create these fabric folds?

IMG_1989

It is not the wrinkles that cause me headaches but the fact that the wrinkles turn into seams at the left.

I am a beginner to Blender and have already tried basic modelling, cloth simulation + shape keys as well as sculpting with the new cloth brushes etc. Nothing is really convincing.

How would pros like you approach this?
Any quick hint would be highly appreciated.

Zoingg