Before you delve into the exciting heads-up waters, it's worth going over some of the key differences that you should bear in mind when playing. Read this before playing heads-up poker for the first time….
Weaker hands get stronger
In a full-ring game it would often be foolhardy to get a decent stack size all-in pre-flop with pocket Tens. That's because there are quite a few better hands possible and, given that you are playing against eight or nine other players, there's a decent chance that when you get action you will be crushed. Instead, you'll generally want at least pocket Queens to get all-in pre-flop in a full-ring game and be confident of having the best hand. When playing heads-up this situation changes drastically. Now that there are just two players relative hand strengths go up dramatically. So pocket Tens now becomes a hand that you would hardly ever fold pre-flop, instead of one where you should proceed with caution.
This applies to post-flop action too. In heads-up poker top pair with a weak kicker may well be good enough to take down a big pot. In a six-max game you'd generally want something stronger, like two pair or a flush, before you allow the pot size to get too big. Of course, this is all dependent on how your opponent plays too. While in heads-up these rules generally apply it might be that you run into an opponent who is still a very tight player. In that case, you would want to adjust your strategy so that you continually run over him by picking up tons of small pots, but wait until you have a very strong hand before committing a lot of chips. The opposite is also true, where a player could be so loose you want to open up your game even more!
Position becomes even more important
By now, you should be familiar with how important position is in the game of poker. The later you are to act in a hand the more information you have. And when you have more information than the other players at the table there is a higher chance that you will win the hand. That's why the button is the best position to be in and why under-the-gun (when you are first to act) is the absolute worst.
Like with most things this concept is accentuated in heads-up play. Now there are only two positions to be in; the small blind (which doubles as the button) and the big blind. When in the small blind you have so much more power than your opponent. Now you can choose whether you want to enter the pot at all, see how aggressive your opponent plays pre-flop and also get an insight into their hand post-flop by observing whether they check or bet when it is their turn to act.
You should focus on playing more pots in position than when you are out of position. On the occasions that you do enter a pot from the big blind you should aim to play aggressively and re-raise pre-flop often, or look to bluff on the flop with plenty of check-raises. Playing in this manner will go some way to reducing the disadvantage you have from being out of position.
Embrace the variance
The fewer players you have in a poker game the more likely it is that the game will be volatile with bigger wins and losses than usual. This is because when you have nine players at the table the correct strategy is to fold most of your hands. If you play too loose then you'll continually be entering pots with the second-best hand and that usually won't work out too well!
In heads-up poker you aren't afforded the luxury of being able to continually fold. If you do that then you will lose a ton of your stack due to posting the blinds every single hand. It's important that you are regularly raising and playing aggressively, even with weaker hands, to counteract the effect of being in the blinds every hand. While this is a very fun – and challenging – proposition, it does mean that you are likely to play more large pots (with weaker holdings) than you might be used to. This will create difficult decisions and probably lead to bigger swings in your PokerStars bankroll.
If this sounds off-putting then it makes sense to start your heads-up adventure playing smaller stakes than you might usually play. By doing this, you will learn the skills and nuances of heads-up poker through experience and also put a cap on how big the swings of the game will be.