One of the key differences between No-Limit and Limit Hold'em is the ability to size your bets.
Sizing bets correctly is an extremely important skill, and one that often differentiates the simply good player from the great one.
There are a variety of situations that arise in No-Limit Hold'em in which the goal, in some form, is to try and control the size of the pot. Bet size (along with betting frequency) is the mechanism that accomplishes this goal.
Remembering the axiom "Big hand, big pot; small hand, small pot" will stand you in good stead.
With a strong hand, building the pot is often the primary objective. To do this, you'll need to figure out the optimal bet size (the one that maximizes your expected future profit). This is often a tradeoff between the likelihood your opponent will call and the size of the bet.
The larger the bet, the larger the pot will be for future bets (which will tend to be a percentage of the pot). The size of your bet also determines the odds you're offering your opponent.
In addition to the size of the bet, position can play an important role in controlling the size of the pot. Having position makes it significantly easier to build a pot (when you wish to do so), while also allowing you to play a smaller pot when that is desirable.
Control the Pot on the Flop
Quite often, your hand is defined on the flop. Generally speaking, you'll either flop to your hand or you won't. Of course, sometimes you'll flop a relatively strong hand, but not a monster - a hand such as second pair or top pair with a modest kicker, for example.
In these situations, the ability to control the size of the pot is important and this ability is greatly enhanced when you have position. Think about it. Whether you're trying to build the pot or trying to keep it relatively small, having position makes the job significantly easier.
To illustrate, if you're first to act and want to keep the pot small, how can you do this? Sure, you can check, but that won't guarantee the pot will be kept small. In fact, checking may encourage your opponent to bet (although he may bet regardless).
Alternatively, if you want to build the pot but are out of position, all you can do is bet and hope your opponent calls or raises. However, if you're in position, the job becomes much easier. In fact, in the vast majority of situations, you'll be better able to accomplish your objective if you're in position.
Imagine, for example, you've flopped a strong hand and your opponent bets. Position gives you the option to raise and build the pot. If, instead, you have a weaker hand and your opponent checks, you can take a free card - an option unavailable to you when you're first to act.
Similarly, with a moderately strong hand, you can bet the flop and then check the turn, allowing you to see the river relatively cheaply.
Control the Pot on the Turn
The turn is often where you can really use position to help you accomplish your objectives. To illustrate, if you have position and the action is checked to you on the turn, you'll often find yourself in one of the following three scenarios:
1. You think you have the best hand and want to either build the pot or protect your hand.
You need to determine (estimate) the type of hand your opponent has. If you believe he has a drawing hand, you'll want to bet an amount that makes it mathematically incorrect for him to attempt to make his draw. On the other hand, if no obvious draw is present and you have a strong hand, you'll generally want to make a smaller bet that he can easily call.
2. You might have the best hand, but aren't overly confident and would like to see a cheap showdown.
This is one of the classic situations where having position really helps. Because you have position, you can simply check behind. True, if you were ahead you've now given your opponent an opportunity to draw for free and potentially win the hand.
But the odds of this occurring are actually relatively small. If you're ahead on the turn (and your opponent doesn't have an obvious straight or flush draw - in which case you'd be more inclined to bet), he can have at most five outs.
This makes the odds roughly 8-1 against him improving to beat you. At the same time, you also keep the pot small.
This benefits you in two ways: Your opponent will try to bluff you more often on the river (which you will call) and he will also tend to pay you off more frequently when you make a value bet on the river (because you've shown weakness on the turn and he's now somewhat uncertain about what you have).
3. You don't believe you have the best hand, but you have a draw.
Again when out of position, you have to decide whether to continue betting (assuming you bet the flop) and thereby risk the possibility of being raised, or to check and hope to be able to see the next card cheaply.
However, when you have position, you still have the option to semi-bluff, but can also decide to take a free card - a choice unavailable to you when out of position.
Vary Your Play
Another critical aspect to playing position correctly is to remember to vary your play. Doing so is a critical aspect of nearly all poker games, but it's even more critical in big-bet games such as No-Limit Hold'em.
One effective way of doing this is by occasionally adopting a bet-check-bet (or call - if your opponent bets into you on the river) pattern with several strong (but somewhat vulnerable) hands such as top pair, top kicker and big overpairs.
By occasionally playing some stronger hands in this way, you'll make it difficult for your opponent to get a read on you. This will allow you to make more money with the best hand, while losing less when you have the worst hand - and that's the name of the game.