I've been slowly improving my HU game somewhat, from the reading I've done this is what I've picked up:
1. Folding the button is almost always a mistake because even with the worst HU hand, which is 32o, you still have the pot
odds to call. If the villain raises, then that's a different story. I used to always fold the button with garbage hands, but I've quit doing that and have been picking up a lot of pots by betting when the villain checks post-flop. Yes, you miss the flop the majority of the time, but so does the villain and when you have position you can bet with nothing and often take the pot. I feel that if your stack size is such that a call will hurt significantly, then it's time to shove with any holding because the BB will hurt worse on the next round and you may well wind up with a worse holding than this round.
2. If you are BB and the villain limps, according to Harrington you should make a much larger raise than normal if you intend to raise at all, reason being that you do not want to see a flop because you will be out of position for the remainder of the hand.
3. As far as specific hands go, again from Harrington on Hold'em, the only two situations where one hand is a big favorite over another pre-flop is a higher pair over a lower pair or two lower cards. No non-pair holding is a big favorite over any other non-pair if there are no cards in common, which was a surprise to me. KQo was brought up earlier, according to Harrington this hand is ranked in the top 20% according to its ability to beat any random holding. This isn't a hand you want to be calling with at a full table when there's a raise and a 3-bet shove in front of you, but HU I don't think this is a garbage hand at all. Again, the majority of the time both you and the villain will miss the flop so in HU play often just having the high card is enough.
This stuff is probably common knowledge for most people here, but it might help somebody and if anyone has a different take, feel free to disagree.