Bluffing is one of the most common strategies in poker and, when used appropriately, can be very effective. Through bluffing you can make players think one of two things -ou can make them think that your hand is much better than it actually is or that your hand is much worse than it actually is.
If you have a very good hand and are quite certain that you will win then you may want to use bluffing tactics to make the other players think that you only have a mediocre hand. The reason for this is that if other players think they have a shot at beating you they will continue to put more money in the pot. If you make it obvious that you have an amazing hand then everyone will fold, leaving you with a smaller prize.
On the other hand, sometimes you will want to let other players think that your hand is better than it is. When you use bluffing to imply that you have a winning hand you can get away with a mediocre or weak hand and win the game!
When you bluff it goes against proper poker etiquette to come right out and lie about your hand (i.e. Saying, "Woo! Pocket Aces!" when you actually have a pair of 3s). However, you can bluff with your body language and facial expression. When you are dealt a so-so hand you can make your opponents think otherwise by flashing a quick smile when you first see your cards. Players who look at their cards multiple times generally have a hand so good that they just can't believe it, so double checking your so-so hand may also make your opponents think it's better than it is.
You can also bluff with your betting patterns. Usually when a player raises it is because he has a good hand. Raising on a weak hand will make your opponents think that your hand is better than it is. By the same token, checking or calling on a phenomenal hand will make your opponents think that you are holding on to a weak set of cards.