Knowing how to bluff and being able to carry it off are two entirely different things. The key to successful bluffing is using it infrequently, and only when your position and the table dynamics allow it.
The aim of your bluff may be to obtain control of the table in later rounds of betting, in which case you would most likely place a reasonable bet (4x/5x the blind), and make it from late position on the table. If you are attempting to steal the pot and/or blinds, then a much larger bet (15x/20x the blind) is recommended. This later action can be performed from any position on the table, but beware of aggressive players behind you if your bet is too limp.
Before attempting any sort of bluff, it is vital that you are aware of the players on your table and that they have identified you as the type of player that would not play a bluff. Many naturally aggressive players are too impatient to set this image up, and want to play bet/raise poker from hand one. Unless s/he is fortunate to find “calling stations” on the table, bluffing aggressively will not work as well so early, plus you run the risk that one of the “stations” will catch on a later card. In fact, the more people there are going into a flop, the more unrealistic it is to try and bluff them.
Other types of player to look out for are slow players and other bluffers. Slow players are the tight players who may try to get to the flop cheaply on occasion, and then follow you all the way to the river holding top hand, but never once raising your bet. It is only when you raise on the river that they will hit you with a monster re-raise, and you know that you are doomed.
Slow players are notoriously difficult to spot, as the opportunity to play like this only comes around infrequently, so you rarely know it is coming until it happens. Bluffers on the other hand, are following the same pattern as you are – play yourself quietly into a game, play one or two good hands, and drop in the occasional bluff. They are also pretty hard to spot if setting up their bluff correctly, and this is why the value of observation and note taking is so essential.
There is now a school of thought which suggests that before you play your first big blind, you allow for a whole circuit of the button when you join a table. This will allow you to identify different types of player and be more prepared for when you do get involved.
Being able to pull off bluffing successfully is an important skill you should acquire in order to play good poker. By integrating it into your game when the scene is set and the opportunity is right, it will prove to be a lucrative option for you time after time.