HU is really no different than short-hand, or really, even long-handed games. Its just that all the things you do well or poorly in those situations will be magnified. Position is key, use the button. Aggression is much more important. In SS2 JHarmon says that describing a heads-up player as passive is just another way of saying he cant win. HU becomes very personal, since you are playing every hand vs the same opponent. So reads are critical. This can be difficult in an online context, but carefully observe opponents betting patterns so that you can identify traps and weakness, while concealing your own patterns. gl.