My hairdresser charges $35 for a shampoo, cut, blow dry, which is cheap by today's standards. $50-60 is the going rate. I always tip her $15, so the total is $50.
Edit: Having read everyone's responses, I am surprised by the number of people that leave very small tips or none at all. Hairdressers and wait staff in restaurants rely on tips, as their salary is very low.
My daugher waitressed through college, and the restaurant reported 8% of all of her sales to the IRS. If someone had a $50 meal, and didn't tip her, the restaurant still reported to the IRS 8% of $50 which is $4 as if she had gotten a tip. She then would be taxed on that $4 as income, even though she didn't receive it. I tip well.