Huntsman's Lodge has a terrific set of tips for running Power Auras as a hunter. I'm not running this addon (yet) on my hunter, but apparently it's pretty old news -- our old friend BRK had some ideas on how to use it a while back. But HL goes even farther, and I like a lot of his ideas, like a star that lights up when Dragonhawk isn't turned on -- I'll admit I make that mistake from time to time -- and warnings for "special circumstance" spells like Lock and Load and Kill Shot.
You can mix and match them all to fit your own gameplay as well, so maybe use some from HL's list and throw in one or two from BRK's old setup. And even if you're not a hunter, the addon is helpful for any class that needs a heads up on buffs and debuffs coming their way. We hunters can get all the help we need though -- HL's list is a great resource for using the addon with our class.