A friend of mine plays HU almost exclusively.
He always tells
me that it's about outplaying the other person. In HU, any A is 3-bet worthy, and any K is 2-bet worthy. You are going to get 3-bet light a lot by a lot of players, so don't be afraid to teach them a lesson with a 4-bet from hands you normally wouldn't consider 4-betting (like AJ).
A HUD, while helpful, becomes less important, especially if you're only playing against one villain. In a HU SnG format, establishing chip lead early is important. Some people will fold and fold and fold and fold, waiting for their premium hands. I prefer to play in a Turbo or Ultra Turbo format, because 10+ minute blinds are waay too long.
But you get them accustomed to folding, and they just let their stack dwindle and dwindle. It starts out as 20 chips here and there, and they get used to doing it, then it's 40 chips here and there. And they're still doing it. Now it's 50 chips... Before you know it you've been 3-bet twice out of 80 hands, taken down 24 pots before the flop, and have a 2:1 chip advantage, and your opponent is sitting with 10 BBs to your 20, and they're still accustomed to folding.
No articles for me to send you to. But play HU more aggresively than you would FR or 6-max.