heads up NL holdem - what to raise with

[montechristo]

so I am starting to play a lot more heads up NL poker and am interested in how badly I am playing. It seems I am raising alternately too much and not enough depending on the weather or some other ridiculousness. Maybe I don't understand reverse domination? Heads up how low do your raising standards go? A2o? K9o? Of course opponent dependent, but assuming a decent opponent who will play back at you, how much do I open up vs. six handed?

thanks in advance from a donkey