Dealing with people on flush draws

I have been running in quite a few people lately who are winning to go broke on flush draws. What % of the pot should I be betting with a over pair or top pair? I don't want to over bet in case someone actually has a real hand. I understand by odds its good people are willing to go broke with flush draws. However, I have taken a few big hits in the past week with people either calling me down with flush draws or even re raising me with flush draws.

I like to bet roughly 2/3 of the pot myself, but that depends on certin factors. Does said opponent hang on to fd's like grim death? If so, smaller bets will do because if they're gonna call you anyways, why give them a big pot if they hit? IMO on lower limits especially, players greatly over value the strength of a fd, and thus are less likely to fold unless given a damn good reason to do so. Sometimes against these players, a massive overbet (pot + 1/2) will be the only thing that will shake them.
Now, on the other hand, if they are a seemingly competent player, I try to give them bad odds. Say the pot is 700, and I figure them for the nut/near nut fd, I would like to bet enough to discourage them calling, yet not too much that they can see I'm trying to discourage a call. Into this pot, I'd say roughly 500.

Though this is all apeculation, of course, and situations vary. I guess it all comes down to what you know or don't know of your opponent, the type of game (ring, tourney), how close you are to the payouts, ect.

Now as far as players re-popping you, depending on the texture of the flop, it's usually fairly easy to define their range. If you feel they are popping on a fd, I find that a smooth call is a bad idea. If the flush card comes, you have no moves, and if it doesn't, they still have the lead on the pot due to the re-raise and therefore can be representing any number of hands that will have your overpair/tp beat and will make it difficult to play with any type of certainty on firther streets. I personally will come back over the top with all my chips, if I feel they are on a fd, and not some type of two pair/trips hand.

in the low limits and small buy-in tournaments, its almost impossible, save for a massive over-bet of the pot, to shake people off flush draws. its just in the texture of most players at these limits to chase em.

First, understand why Villain's willing to go broke on a draw.

For a flush draw on the flop, where you have no pair and your opponent has top pair (and he has no way to improve beyond a straght), you've got 9/47+9/46 = 39% chance of hitting your flush. It makes sense to put up $1 if you're opponent is going to give you $2 if you hit.

For a fd + open ended straight draw on the flop, you've got a monster draw - you're actually a favorite to win the hand against an opponent with a single pair - you've got the 9 flush cards and 6 more cards to make your straight (don't double count the 2 straight cards that also make your flush), so 15/47+15/46 = 64.5% - so even if you have exactly nothing on the flop other than your fd+oesd, statistically you're ahead of Villain.

Draws come in different combinations and different situations - maybe you think you have two overcards plus the fd, and can add those six outs to make your fd a monster draw, maybe you have a gutshot sd + a fd, which is pretty much a coinflip against a single pair, etc.

Villains also come in different flavors - villains who understand the above and villains who don't - so sometimes villain is just gambling and sometimes villain is making a play as a favorite and knows he's the favorite.

How do you combat this? First, try and figure out whether villain understands the above. If he understands the above, you can combat the 9 out flush draw by making it too expensive for an intelligent villain to call - 2/3+ sized pot bets are a good way to accomplish this, as it doesn't give the correct odds to call. A knowledgable villain will generally fold here (not going to talk about implied odds here, post is already too long). If Villain understands above, you won't be able to get him off of a monster draw - in fact, he's likely to raise you and try and get your money in the pot as quickly as possible.

If Villain doesn't understand above, simply make it too expensive for him to continue drawing to 9 outs with 2/3 sized pot bets, and be very careful if it looks like he may have more than 9 outs. If he's going to simply gamble on the 9 out flush hitting, you will win more money over the long run, though you will lose in many situations in the short run (generally you'll lose 39% of the time, but you'll win 60% of the time). You want to make sure you're getting value for the 60% of the time you'll make money here.

If I'm at a cash table, and I know someone is on a flush draw, I bet as much as I think they are willing to call. That sometimes means overbetting the pot.

If I'm in a tournament, I usually bet 1/2 to 3/4 pot. (with exceptions based on chipstacks and blinds) Here, you may want to keep the pot smaller to keep from being crippled due to a suckout.