Whenever I find myself in a flush draw situation, I try to let the pot odds
decide for me. If somebody's betting big at me, I just toss them. (unless we've got big enough stacks to give me serious implied odds) In tourneys it's hard, because if you're not building chips, you're falling behind. That's why I stay away from betting flush draws unless I've also got a pair or something else that might hit.
One thing I really try not to do is chase a flush out of position. In position, if you hit your draw on the flop, you can semi-bluff bet it, then you might get to check for a free river card if that fails to pick up the pot.