Heads up poker refers to a game where two players battle it out for a pot. Each player alternates both the button and the blinds (small and big). The dealer (the small blind) acts first before the flop and acts last after the flop.
Major Differences from Conventional Poker

The fact that only two players are at the table radically changes the odds of the game. Most people will assume that having only one rival for the pot means higher odds of getting high-scoring hole cards, with better than even chances of getting a good hand on the flop, turn and river. This view ignores two things – one, that there is just as equal a chance of getting ‘poor’ hole cards or even worse cards on the flop, and secondly, that the other player may be getting the better cards off the deal.
At the same time, since there are only two people playing – and alternating blinds – a heads up poker player has no room for a leisurely game. Every hand (or almost every hand) should be turned into a win or else, a player will end up with a very short stack sooner than expected.
Playing your usual ‘cautious’ game may be a no-no because your opponent will be bearing down on you to ‘put up or walk out’ – some games limit the number of checks you can call, and constantly folding quickly depletes your bankroll. The situation dictates a different mindset when playing heads up poker – you have to be more aggressive and take more ‘risks’ than you normally would.
Aggressiveness is Key
The most important thing to remember is that the odds of getting good or lousy hands is about equal for you and your opponent – so be prepared to throw out your ‘usual’ conventions or rules of thumb when the cards are dealt. You may be used to checking or folding when dealt low pair hole cards; in heads up poker, take the risk of raising on the flop – your opponent ‘may’ have better cards but chances are good that you can make up for this during the flop, turn and river.
Aggression should be carried out at all stages of the game, from pre-flop onwards – unless you see that you truly have a poor hand and have no choice but to fold. Even then, timing is everything in establishing your image to your opponent – showing confidence even with weak cards is one way of confusing the other player and hopefully, pushing him into mistakes.
Bluffs are harder to play in heads up poker, especially if you’re easy to read – You have to learn to reduce your tells in one-on-one poker; showing any sign of weakness will place you at a disadvantage, and there is nothing worse than being pushed into this in heads up poker.