How to shade leather with pen?

Question: How to shade leather with pen!?

I'm attempting to draw a leather jacket, and it's my first time trying to get a convincing leather look and I'm not sure how to shade it or where to add shine or how to wrinkle the material!. My medium is obviously pen!. Any help would be apreciated, as long as you know what you're talking about!.

Thank you!.Www@QuestionHome@Com

Best Answer - Chosen by Asker:

Here are some examples you can look at!. It's really all up to you though!. I think leather would look more convincing if the shading and highlights are sharp-edged instead of blurry shadows and shine!.

http://browse!.deviantart!.com/!?section=br!.!.!.Www@QuestionHome@Com