Hair Dressers.... what do you consider a good tip?

What is best, what is good, and what is ridiculous (besides no tip)?Hair Dressers.... what do you consider a good tip?
I am a hair stylist. What's rediculous is spending 3 1/2-4 hours on someone's hair %26amp; they like it %26amp; thank me but say: ';Oh, I'm sorry, I don't have any money for a tip, I aint got no money';.....It's a service %26amp; just like a waitress, we rely on our tips, you wouldn't go out to dinner %26amp; ';stiff'; the waitress, right? But anyways, the proper way to tip is 15-20% of how much the service costs. 15% for average, 20% (or more, lol) if you really liked your hair/service.Hair Dressers.... what do you consider a good tip?
I usually tip between $10-$15 depending what service I had done. I don't think you should go below $10. But like that other person said. I've heard you're supposed to tip about the same you would at a restaurant 15-20%.
5 bucks, 3 bucks, 1.