Why are my bluffs so obvious?

[Crispyk]

The biggest leak in my game has to be bluffing, I play very very tight aggressive, I wait for the hand and i shoot out hard at it. But The biggest problem i have is when I am heads up in a hand with someone else, and the flop misses me. Once in awhile i'll shoot out at it and try to win the small ones. Yet it seems like every time i do I get check raised or reraised hard. I don't know if my bluffs are obvious and they are exposing my weakness. Or if i just keep bluffing into a better hand. My question to everyone is, what is a good amount to throw out at a small pot when you miss. Should you bet the pot, should you bet 1x bb 2x bb...etc.... I'de love if someone could give me some advice on how i should play these. and what a good amout to throw out is?