It's a necessity, I can't imagine anyone out there being a winning player in any stakes without bluffing. Not only is it great when you actually get it through but there is value in being caught in a bluff as well. They are less likely to believe you the next time you actually have a winning hand and might call down with something weak. I believe that's why some people think it's a good idea to show the bluff at times when it gets through.

The trick is picking good spots and evaluating more the cards you think your opponent has rather than the opponent themselves for the most part. Obviously a tight player who only comes in with say AQ+ or TT+ is easy to bluff on a board that has 2 6 8 9 8 as they have probably missed their top pair and if they've checked down you could have bet the turn or river. This isn't most opponents though, you generally have to hope they understand what you are likely to have and if the cards fit that range push the action. Sure sometimes you get caught but like I said there is value there as well in your table image.

It can be nerve racking to bet 2 streets on a pure bluff but it can also be effective, as long as you are only using it a smaller percentage of the time. A lot of people loose their nerve on a bluff and don't fire on the river or they don't play the hand the same way they would if they actually had a good hand and that's where it falls apart.