Bluffing is situation dependant, remember that. If you raised before the flop, people will usually respect your bets on the flop if an ace or king comes. When the third of one suit hits the turn or river, sometimes you can represent the flush (unless they were on a flush draw all along). If you bet and keep getting called, examine the board. Is he chasing a flush or straight draw? If the turn and river seem like cards that missed a drawing hand, it's usually correct to make a bet on the river. If they missed their draw, they will fold and you will pick up a nice pot.

In order to be a consistently good player, bluffing has to be a big part in your arsenal. How else can you take down a pot with 250? Bluffing. Remember that your bluffing needs to tell a story, if they believe you have it, then it doesn't matter if you actually do.