Hi S.!!
I know you asked for downtown, uptown, and North Dallas specifically, but... my recommendation is in Irving, not far from you in Carrollton. Her name is Patricia Drake and she has a salon inside Plaza Salons on O'Connor. She will make you sassy and give you a great makeover!
Here's her info if the distance isn't an issue for you. I've been seeing her for several years and at least 6 of my other girlfriends are devoted to her and have been for at least 7 years or more.
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2700 North O'Connor Rd
Suite 112 - Studio 21
Good luck with the new you!! Tell her C. sent you, she takes referrals from her clients but doesn't typically just take new clients.
-Char