Ok so here's the background story -
I have an awesome hair stylist that works at an exclusive salon. So since I'm not a member she cuts my hair on the side at her house. I have used her since I was 15 (I'm 22 now). She wasn't always at this salon and when I first started using her it was at another salon that I could use (not-exclusive). This arrangement (she cuts my hair on the side) is a new situation.
I had my hair cut about a month ago - basically just a trim. She charged me $25 and I gave her a $10 tip. I wasn't sure about tipping her and how much. So I just did that.
Here is my question - I am going to her house tomorrow night (Friday) to get my hair cut again - this time a complete new style (probably about 5 inches cut off). She will probably style my hair afterward as she generally does this.
Should I tip since she is getting all the money and doesn't have to share with owner, etc?
If I should tip ... what percentage?
Thank you!! 
I personally think that the $10 was well over what you needed to tip for the trim (40%). However, since you tipped her last time, I think you are stuck tipping again, regardless. I would just tip the standard 20% and if you feel the need to tip more, go ahead. However, she's charging you the price for the service (especially if she's doing this on her own), the tip is just above and beyond. If she's not paying fees to anyone, I don't think you really need to go for a 40% tip each time. I'd just do 20%. That's the widely accepted amount.