How to paint realistic reins and leads?

Not just the pen tool reins; how do you paint those really realistic, flat/square looking, detailed, shaded reins? I'll pay someone who knows how for a good tutorial.

You use photoshop or gimp?

I would like to know also, I use Photoshop!

I draw them with pen tool, then i use 1px brush and pure white colour. I set opacity and flow to 25-20% and paint all the details. Then I add a shadow underneath and fix details with pure white and opacity 40-45%