What is the point of playing a huge multi-table poker tournament just to get knocked out once you reach the final table. You may have had a few 2nd place finishes, but the 1st place finishes pay the most. Knowing how to play heads up poker is the key to maximizing your success in online poker.
First you need to be aggressive. However, it should be a smart aggressive. Do not let your opponent see any cards for cheap. Make your opponent pay to see the flop. This will keep him from catching cards when he has a marginal poker hand. Throwing out some good bets is a sure fire way to steal some blinds when playing against a weak player.
Pay attention to your opponents style. Does he just call or does he re-raise? Does he check more often than raise? These are all signs you should be reading when analyzing your opponent. Take note of what hand he shows in a showdown, and break down how he played that hand from the flop. Did he even hit the flop? When did his card come? These are all questions you should be asking yourself, and you should keep a mental note of how he played out his hand.
Be aware that as you analyze and read your opponent he is doing the same same to you. Avoid obvious tells like playing the same style hand after hand. In order to keep him guessing you need to change gears. Play tight for 10 minutes then loose for the rest of the match. Vary your style any way you can.
Noticing their betting patterns is another good way to help you win. Ask yourself questions about how they bet when they have a strong hand, a weak hand, or a drawing hand.