I actually gave something like this a try last week.
Here's my feeble attempt (you may need to scale the picture to get a better impression how it looks on a miniature rather than a blown up picture):
In addition to getting darker folds I fancied painting a few worn areas around the edges by leaving streaks with little to no paint coverage. The idea is that the material isn't quite torn yet, but worn off so that you see less of the fabric and instead get a slightly see through effect.
Hardly an expert's work, but maybe it helps.