Poker bluffing is when you or someone else bets or raises the bet in accordance to your hand, which you lead others to think is better than what it actually is. Sometimes it might be best to bet for value instead.
The best way to know when to bluff in Poker is when you get to the point when your opponents cannot decide whether to raise, call or fold. Technically, you should bluff at Poker in proportion to the pot odds. The chances against your bluff would have to match your adversary's pot odds.
However, intuition also takes its part in Poker bluffing, and nothing beats your own judgment as to when to (or not to) bluff and aim at/risk a higher profit. Of course, this judgment comes only with much practice and learning.
In the early rounds, Poker bluffs should be fake, i.e., bets and raises have little chance of winning if called, even with more cards to be received. So why bluff in early rounds? Because Poker bluffing helps to keep the other players edgy and guessing.
A "fake bluff" may win if your opponent folds or if you happen to make the best hand with cards to come - in which case, you are more than welcome to try a "real" bluff, because the odds are in your favour.
This is the thing with bluffing when there are more cards to come: you get called and have to decide whether to continue bluffing or not. Only experience will tell you the right thing to do regarding when to bluff in Poker or when to give up. A trained player knows when his adversary is getting stronger or weaker and bluffs accordingly. For instance, if you do try to make a real bluff when there are more cards to come but get raised, you have been busted, so give up and move on to the next hand.
In this case, Poker bluffs are for real. All cards were given and your hand is not a winner, so if you get called you will not win. So should you bluff?
At this stage, bluffing is to be avoided if the chances of your adversary calling are bigger than your pot odds. If, on the other hand, chances are your opponent will fold enough times for a bluff to become profitable, go ahead.
Consider, of course, that the bigger the pot, the bigger the odds of getting a call on your bet, no matter how fair the other player's hand is.
Knowing when to bluff at Poker is useful if you can assess your probabilities of pulling it off. Obviously, you are going to bluff when you consider your opponent's hand to be weaker. On the other hand, if your hand is weak and you think your adversary's is too, avoid bluffing altogether, for he will call your bet.
Knowing when to bluff at Poker is highly subject to your ability to read other players. Usually, it is easier to bluff against a tough player than a weak one, because the weak one will call at the slightest chance or suspicion of bluff on your part especially if you have a reputation of bluffing in Poker.