Mens fashion tips

I’m kind of shy and awkward, so don’t really know how to tip my hair stylist properly.
Should I hand her the money right after she finished cutting my hair or should I put it in an envelope and give it to her? Or should I give it to the person at the front desk?

My sister cut my hair for years, but she’s moved away and I’m now going to a fairly upscale salon (at least for my small town). The person cutting my hair is the owner and she charges $40 for a cut and style. How much should I tip her? Do I tip her more if I decide to get color or a perm? Is it based on the amount I’m spending? I would really appreciate an overview, I haven’t gone to a hair salon in over 20 years - yikes! Help!

I’ve never actually known, and I just found this new place to go, and they seem -really- professional and they’re kind of expensive.. so, I don’t really want to offend him or her by not tipping them the correct amount.
I’m sorry. I guess I asked wrong. I don’t need tips on how to style my hair, lol. I need to know how much -money- I need to tip my hair stylist after he or she is done cutting my hair. =|