Even before the cards are dealt, you start playing Poker. Imagine you are playing in a Poker casino with strangers: you need to observe the other Poker players and pick out their ticks. Are they the nervous, timid type, or are they aggressive and boastful?
Conservative, edgy players are bound to call at the slightest hint of Poker bluffing on your part, so avoid bluffing them. What to do with such Poker players? Bet any likely favourable hand.
Tough Poker players are more likely to bite the bait. However, reserve your fair hand bets for value, because it is unlikely such a player will pay off with his worse hand. When he calls, he will want to show off his winning hand.
Poker position is of utmost importance. Against a tough player, your bluff will work best if you play in early positions. If, on the contrary, you happen to have a strong hand, avoid betting in early Poker positions so you can blow your opponent's bluff.
Bluffing is an art, so treat it like one. Do not fall under the easy path of using the same bluff on everyone. If all cards are out and you try to bluff more than two Poker players, you are bound to fail. Your best chance to make profit out of it is to bluff against each player separately. It is a pure rule of "divide and conquer". If you have them united against you, you are doomed.
Some players are known bluffers. They are caught bluffing and lose. However, this is one of those rare times when being caught "cheating" may actually work in your favour. Known bluffers are granted a lot more calls for their legitimate hands than non-bluffers. On the other hand, known callers may also have things working in their favour, as tougher players will restrain their bluffs on them, fearing a call on each move they make.
Other players are supposed non-bluffers. This allows them to win great pots when a bluff is unexpected - which is the successful kind of bluff. It takes many calls on legitimate hands to compensate for one good pot. So unless you are playing against tight(er) players, bluff a little less than optimal to get more profit.