I still don't understand raising flush draws

[celiboy]

The only book I've read is Matt Hilger's which is decent but does not fully explain raising a flush draw on the flop. I think these are the reasons. Let me know if these are right, if there are more, or whether I do not understand the concept fully.

1. Cleans up your outs. If you have A/9 suited for example, raising could get a better ace out of the hand so that if an ace hits on the turn or river this could now give you top pair

2. You could win the hand outright - unlikely, but a possiblity.

3. Disguises your hand. For most beginners this is not a standard play and when the flush card hits, they will not put you on a flush and will pay you off on later streets.

4. Effectively increases your odds. If you raise and get callers your odds are improving as you are only putting in a fraction into what will now be a bigger pot.

I am uncomfortable raising a flush draw because to me it is incongruent with a fundamental rule of poker. Bet/raise when you feel you have the best hand and fold when you think you are behind unless getting proper pot odds. We are raising with what is the worst hand at the moment so it's a tough concept to grasp.