It's a very complex situation with many answers based on many scenerios. Here's my general answer...

When flopping a 4 flush your first priority is to find out how the flop hit everyone. So you evaluate the flop to see how likely it is that it helped anyone else in the hand, and furthermore whether they would raise you if you bet into them. If you're sitting in early position 5 handed and two broadways flop, then obviously you must check and call with odds. otherwise fold.

You should get into the habit of betting the pot amount on the flop every single time you feel there's a chance you can take the pot down right there. That's regardless of position. You should also always bet the pot amount from any position if you feel there's a great chance someone might come along but won't raise you. It takes a while, but eventually you'll be able to successfully pull this off in early positions. This is why it's NOT recommended to play suited aces and kings from early position. They are very difficult to make money on even if you hit. Sometimes you end up in the blinds 4 flushing however, so that's the way it goes.

BET YOUR DRAW FOR ACTION

Extracting implied odds out of a flush draw is an important action to take when you're 4 flushing. Flush draws have very bad implied odds when your opponent has any indication that you're drawing. That's why it's important NOT to underbet the pot at all if you take control. You want people eliminating the possibility of flush in their own minds so that you get payed off when they hit stuff like two pair, trips, or a straight to your winning flush.

An advanced technique is to check raise in early position when your two flush cards in hand are overs to the board. That's because a check raise completely disguises a draw (since very few players would do that). It's correct because you have potentially 15 good outs, and you gain fold equity against your opponent when you check raise. When drawing to straights and flushes, it's good practice to act like your trying to CHASE YOUR OWN DRAW AWAY. It stimulates action all day long. Once again you can afford to do this because you have fold equity against your opponent. I'm bad at poker math, but your opponent folds often enough to give you a profit to play this way if you have good reads.

Whatever you do, DON'T MIN BET A FLUSH DRAW. Opponents will make you pay dearly for a draw they never intend to pay off if you stick around for it to hit (after you call big incorrect bets). Next time you min bet a flush draw, shoot yourself in the face. Just end it all right there. Tell yourself you're doing the complete opposite thing you should be doing. You don't want to tell your opponent you're drawing. You want to INSIST to them that you aren't.

These are cash game techniques. Late in a raising blind tournament is another discussion.