I just started using Power Auras again. I'm not real crazy about Blizz's auras.
I will admit to being a total noob and doing copy/import for many of my auras, then fiddling with them to my liking. I can do simple ones, like debuffs to GTFO of the fire, or whatever, but need help with one for Careful Aim.
Another option would be to have your unit frame mod display percentages of health along with actual health numbers. From my dealings with POWA, this seems like it would be a lighter solution.
You can't shake the Devil's hand and say you're only kidding.
I use IceHuD so I can see my health, focus, and enemy's health, and enemy's mana in the middle of my screen. It also shows HP% so you can see when you are in the first 80% pretty easy.