On the beginning you have to be patient, because usually one opponent beat the other, then you can heads-up and the opponent maybe too agressive. This is a benefit which you can take advantage of play with great hands and then turn the game on your side. If you have very good hands (AA, KK, QQ) on the beginning you can try to go all-in or call an all-in and after that you start the heads-up on the 1st position.