Heads-up Limit Poker

I think the best part about heads-up limit is that it really teaches you every single human aspect of limit poker in all it's glory. Aggression, hand selection, bluffing, trapping, reading, value betting, folding and lastly, pot odds. Probably in that order as well. I'll give a quick pointer on each topic:  

Aggression - The poker pro's weapon of choice
The weak of heart get steam rolled with extreme prejudice in heads-up poker. You have two ways of winning a pot - you show the best hand or your opponent folds. You know in the poker books where they talk about playing poker without even looking at their hands? That's the value of aggression right there. Imagine that you DON'T see your hands and NEITHER does your opponent. In this scenario, the mathematical implication is that you will win 50% of your showdowns long term. What does this mean then? You need to cause your opponent to fold more often then you do. There is thus only one viable poker strategy - bet and raise.  

Hand Selection - Play with what you have
Since we CAN actually see our hand, the real value is putting money into the pot when you have the best of it and not putting money when you don't have the best of it. Too many people I'm playing with in limit heads up games aren't penalizing me enough by letting me see flops for free after posting the BB. Or they let me limp in from the SB without fail. Heads-up poker teaches you to always raise with those Aces, Kings, Face/kicker, mid-high suited connectors and pocket pairs because they'll reap long term value. It makes you accustomed to raising for value and playing out on a flop whether or not the cards hit or not.  

Bluffing - Pushing your opponent out of pots
Most of the time in heads up poker, you and your opponent won't hit anything on the flop. This is where bluffing and aggression come in, because you ALWAYS want to take down the pot if you and your opponent have nothing. The flop is like the introductory sword fight, where you declare your intent to fight and your opponent stops to decide and walks away or challenges you back. A lot of feints and fakes on the flop. Then when the turn comes, that's where the real action is, because with good precision, you can make a lot happen with a check-raise bluff or a raise behind the action. If your opponent was merely feinting an attack on the flop, you'll have caught him with his pants down, regardless of what you have. Looking and observing for those small little patterns or timings from your opponent is the key to this tactic. And sometimes you simply toss one out to see what happens. In the event you get caught red-handed, then you switch to a no BS mode and draw your opponent in for the kill by using your own bluffer's image to your own advantage.

Trapping - Keeping your opponent off balance
When your foe thinks that you're not being honest, that's the time to trap him for his money. A check-raise / raise on the turn that gets called in addition to a river bet nets you 2BB just from that play and most likely another 1BB from the pre-flop and flop. You could thus fold on the flop on an unraised pot four times in a row if you could pull a trap every 7th time. So when you're up against another aggressive opponent as well, who simply likes to run you over with bets, simply sit back, let him do the betting and hammer him with check-raises and raises when you have a hand. You can afford to fold when you have nothing, since your traps will make up for it. And if you have Ace high or low pairs, you can still flat call to showdown if necessary to shove the proverbial stick into his spokes.  

Reading- Spotting those tells and working them 
Trying to figure out where your opponent is in a heads-up poker game is a little like trying to beat someone at a prolonged game of rock-paper-scissors. They only have three options and it's to you to guess what they're doing. If you're right more than 33.3% of the time, let's say 35% of the time, then you're mentally beating them long term. If you think rock-paper-scissors is luck, hah, think again. You all know Phil Gordon right? He's part of Team Tiltboys, rock-paper-scissors theory / world champs extraordinare. Poker and especially heads up poker is the same way. You make those reads and you're making money. Making the read is all about discerning patterns in their behavior that are statistical anomolies. That's why you pay attention - how often does he check-raise, does he have it when he does, will he bet low pair, will he bet draws. Usually you can't just figure this out with one action on your opponent's part, so you often have to raise on the flop or call and see the turn to figure out what's going on. Because with only one action, there's only 3 choices to choose from - bet, check, call. By adding in a raise or calling the flop, that increases the options from 3 to 9, bet-bet, bet-check, bet-call, check-bet, etc.. This tells you a whole lot more than just 'Oh I think he's bluffing because he bet on the flop with low cards showing!' vs 'Oh I think he's bluffing because he bet on the flop with lowcards and is now checking the turn'.  

Value Betting - Extracting extra big bets
Value betting is simply getting in that turn raise and river bet so that your opponent doesn't see a showdown for cheap when you got a hand. Even when your hand is a little iffy, you toss that sucker out and at least gain some fold equity from it if he's tight. If your opponent is loose, you get some equity from the bet with Ace/X calling you down. Too many times in games, I see opponents check down on the river with a superior hand because they're scared I might have them beat. If they're going to have me beat 80% of the time, and I'm going to be calling the majority of the time (I am on the river, after all), it's a very worthwhile proposition. In heads up, there aren't a lot of draws that go on, so an opponent sticking with you to the river is probably calling with mid-pair or low pair and least often a monster. Getting that extra bet in is something that you shouldn't be afraid of doing.  

Folding - Knowing when you're beat and getting out of there
Knowing when to get rid of a dominated hand is pretty big, especially if it can save you from a big bet or two. Often you won't realize it until you're down to the river or turn, but the willingness to drop a hand when you are sure your opponent isn't bluffing is just like extracting an extra big bet of your own. Lots of times in a full ring game, it's almost impossible to fold with some of the odds the pot is laying you, such as top pair / top kicker when the pot shows something like 20BB to a single raise on the river. You only have to win 5% of the time in order for this call to be correct. In heads-up, the pot is often more often 3-5BB or so, giving you a good reason to fold if you're certain that you're beat. Once the pot becomes larger, then it becomes harder to fold at critical points like the river, given that the pot is laying you very good odds at that point. The key is to fold early and when you're in trouble rather than late and committed over your head.  

Pot Odds - Counting your outs correctly and integrating them
Pot odds is actually the least important in heads-up, because rarely will you call because you are 'getting odds'. If anything, if you have odds to call - BET! Play those flushies and straight draws aggressively, because whatever odds you are getting, aggression gives those odds a skyrocket value with folding equity tossed in. Even with a inside straight draw, it's not a bad idea to bet if checked to you or first to go, because you still have the possibility that your opponent might fold to you (likely in heads-up). If you miss your draw, you can keep attacking and hope he folds, or by miracle, you may even hit your draw and have a very well disguised hand that's perfect for trapping.  

Conclusion - Heads Up Poker Strategy 

Well, that's my quick and dirty tips to heads-up limit poker and effective strategy in the game. Playing this type of 1 vs 1 poker will definitely be a difficult and struggle at first, even for the seasoned texas hold'em player, but it's a skill that becomes very valuable for almost all players, as tournament poker players benefit substantially and limit players sometime have games that become quite short-handed.