I got brave and bought Karma. I want to be the best Karma NA... how do I play her to best of her ability.

You wait for the rework

AP karma isnt that bad mid, you aren't the assassin type but you can clear/push so hard and sustain yourself as long as you have blue/mana regen items. AP Karma is also fun in ARAM/ABAM

Karma is all bought the cookies.

Best Karma NA will still have 40% win rate.
You must accept it She was built to bottom lane with Tristana, it seems. Perfect synergy.
Do that.
Spellsy (plat support) went on a 6 game Karma spree and did alright. Not good, but alright.

Just don't rush Lich Bane on her, it sucks and has nothing to do with her kit.