You helped me so i am trying to help u there.
With the Flushdraw its kinda tricky and u can play it manyyy different ways.

Against an opponent who cbets much.. may it be pot may it be 2/3 pot, un can raise it kinda small and get him to fold with 30-50BB Stacks.
If he calls well its not the worst because u can hit ur flush + maybe take a free card + maybe take it away on future streets
If Villian shoves here u have to consider.. u are 2 to 1 to make ur flush on the river.. do u get those kind of odds? do you have overcards to your flush which give u some more outs? If yes then call.. if u don t have the proper pot odds and outs to call fold, if u don t have a dead on read he is bluffing.

Against an opponent who is kinda weak more of a calling station and he bets pot on the flop i like a call more because he most likely has a hand and will not fold to a raise. You surely have the implied odds to call one on the flop with 30-50BB if its not a shove.
If i miss on the turn i most likely fold to another bet becaues the implied odds decreased drastically and if you are not in position u are not surely getting paid.
Say you call on the turn a 100 Bet into a 300 pot.. u were getting 3 / 1 u need 4 / 1 to continue so u have to make sure u get another 100 chips in on the river,  else u made a mathematical mistake.
So i often give up on the turn if i have no combo draw and villian bets near to pot again.

If i am short against an aggressive opponent.. say 20 - 0 BB i almost always shove over his contibet or if i think i have an edge i check in position if villian makes no bet and take the freecard, trying to hit the flush on the turn.

so that are some scenarios if u wanna know more on a specific hand feel free to ask =)
maybe some of the pros can comment if i am right on my view or wrong ;)

Yeah i forgot one... if villian often goes broke with middle pair late or shoves with middle pair.. u have to see if u have 1 or two overcards to that pair and then calculate your pot odds and outs properly.
In the end it all comes down to the mathematical correct decision if the cards are face up.

Greets,
N0W

 I use to fold flush draws oop against a strong bet on flop,is it a mistake?The matter is that I'm paing just to see the turn ,wich I hit about <20%times(I'm talking about pure 9outs FD),so calling the pot is cEV-,isn't it?Ya,many times he doesn't fire turn again,but you barely got the right odds if he NEVER does.If you are going to answer my wit the IO tingh,I think the IO are overestimated in this kind of spots,1st are very poor when the pot goes big,and also is hard to get maxvalue oop when a flushcompleter comes(IO are wayyy bigger for OESD)

Kind of a very large question here.

Generally, if you can figure out what your opponent is betting pot with (IE how often, what kind of hands he's shown down in those situations) you can play the hand much more effectively.

Against some very wide c-bettors (both in limped and raised pots) you can check call, lead the turn with a flush draw for maximium fold equity, fairly low risk and a decent plan for virtually every river card.

Against a guy that usually only pots with TP type hands, you might want to flat call him at times and reevaluate on the turn if you're deep stacked. Why?  Because you know when you hit your hand you will quite often get paid off nicely from his hand, since you're deep stacked the amount of chips you're losing when you miss your draw is fairly small compared to the chips you win (his stack) most of the time you hit your flush.

If you're shorter stacked, facing the same type of "only pots with strong hands" player, you may just check fold in this spot.  Raising over his lead will just get a call/shove from a stronger hand and he won't often fold.  Calling doesn't look attractive either because it costs you too high a % of your stack to call his bet and you won't get too many more chips short stacked if you do hit your draw.

The main lesson is that draws of all types are generally less valuable shorter stacked than deeper stacked.  Many players don't take this into consideration and end up losing way too many chips when effective stacks are short with their draws.

However, like everything in heads up sngs, there are exceptions.  If a guy is potting quite a bit and you're short, you can just check raise many draws for maximum fold equity.  You may be behind when he calls/gets it in vs you, but all the times he folds when you raise will surely make up for that.

Just try to identify what your opponent is doing, then formulate a plan with your hand to extract the maximum amount of chips against him (or lose the least), sometimes that means folding, sometimes that means calling and sometimes that means raising.  The stacks, combined with the opponent's tendencies will often help you make a much more clear decision.