Reading your opponents is extremely important in heads up play. When you are heads up it is more important to play your opponent than the cards.  If you are able to get a good read on your opponent, you will be able to beat them. You should watch your opponent’s betting patterns and when you do show down a hand, go back through the hand in your head to see what your opponent did and how they played that hand.  After awhile you will begin to see a pattern in the way they bet and play certain hands.  You might notice that your opponent will always raise 3 times the pot when they hold an ace or that they will always check the flop, when they miss it.  You must use this information to your advantage.   

If you know your opponent is passive, then bet into them if you are first to act.  If you have position and act after them, then bet if they check.  If your opponent is very aggressive, then you may want to trap them.  You can let them bet and just call.  This will likely further induce your opponent to bet on the next streets.     

Usually in heads up play the aggressor wins most of the time.  If you raise aggressively pre-flop, you will force your opponent to lay down a lot of hands and you can pick up the blinds.  Since you only hit the flop about 30% of the time, it means that your opponent will miss the flop 70% of the time.  If you are aggressive and bet on the flop regardless of whether you hit it or not, it will be hard for your opponent to call when they will be missing the flop most of the time.  If you can steal a lot of blinds heads up and take down a lot of pots on the flop by being aggressive, you will end up profiting. 

When you find yourself playing against a very aggressive player, you must choose your hands wisely.  You should not try to be even more aggressive than them.  Folding your garbage hands is a good way to wear down your opponent.  When you do have a good hand, you want to raise or re-raise them rather than calling.  This will put the pressure back on them.