Bluffing is a part of Texas Holdem Poker, but it's not a huge part of the game. It's a tool that can be used at times, but not too much. The reason you can't use it too much is because it rarely works with large table games and with low limits. If you're playing a large table there is a very good chance that at least one person has a good hand, and odds are there are more than one good hand. It's hard to bluff someone into folding a good hand, let alone bluffing more than one person into folding a good hand. So you can't really rely on bluffing for regular wins. Instead the real use of buffing is to use its to setup uncertainty in the mind of your opponent's. If your opponent's witness you bluffing and you lose, they know you have it in you to bluff and that can help you disguise your game later. Bluffing Texas Holdem Poker can help put a monkey wrench in the other players decision-making.
No limits Texas Holdem Poker has more of a bluffing factor then low limit large table games. This is because of the frequency of heads up play and the power of betting large amounts of chips psychologically.
Remember the best time to bluff is when you feel you have a edge over and opponent, but not necessarily on the hand. You are heads up on an easy folder and are the chip leader for example. Don't bluff just because you invested so much money into a bad flop and feel the need to bluff your way out.