As Mat has stated there are a lot of ways to deal with this task, but it all depends on the end result your looking for.

Game Asset - Polygon Plane Texture (with Alpha)
Photoreal Image - Model it to detail and/or use above
Film/TV/Animation - Model it to detail as above and use cloth to get it react correctly

These are my solutions and others will have there own ways. I suggest you look at what your end result wants to be and use that to get your workflow sorted and how you want to tackle it.