When should you 3bet bluff pre flop with a marginal hand?

I have tried doing this a few times, it worked out 3 out of the 4 times ive tried it when i 3bet pre flop on the small blind with hands such as small suited connecters and king 8, king 9 suited and got the first guy who raised to fold but one time i tried to be a little cocky and i raised on the button with 8,3 offsuit to try and steal the blinds but the big blind 3bet me, and i decided to try and get him off the hand by 4betting but he 5bet shoved so i had to fold in the end haha. He turned over queens so i picked the wrong time to do that , when should you 3bet or 4bet bluff pre flop?

Well don't just do it just for the sake of 3bet bluffing. You have to ask yourself why you are doing it.

If the person played 2-3 hands total in the tournament, and all of a sudden raises from UTG and you decide to 3bet bluff, expect to get 4bet shoved on since he is so tight.

On the other hand, if a player opens up really wide but folds a lot to 3bets, then he is a better candidate to 3bet since it's more likely to fold.

Yeah the guys i normally do it to is someone who raises with any 2 suited cards (this is live play not online) but obviously everyone does get a hand from time to time so its difficult to tell if he actually has it or not haha, i do avoid 3betting tight players unless i do have a monster but my style of play is aggressive, i like to take control of pots and raise with junk from time to time and bluff my way to winning pots (i don't do it loads of times since that will be suicidal but i do it every now and again)

I see you bought my video on how to 3bet bluff into someone who has you dominated.

I won't 3bet bluff with junk unless the pot is unopened and I have position. I have tried raising to an opened pot only to have the ones in already call, then I have crap and 90% of the time have to fold post flop.

what video is that haha? And shadow451 don't you try and c-bet the flop and maybe a double barrel on the turn as a pure bluff if called to get your opponent to fold? I do that sometimes with rags and it works 90% of the time, if i get called on the turn i usually give up but i am capable of treble barrelling with nothing and it sometimes gets people to fold top pair etc haha

This never seems to work for me, only rarely. I guess you have to have very good timing to pick the right spots. I would like to be able to do this more often myself sometimes too.

Maybe it works better playing live than online since i've heard that online players call a bluff on the river with like bottom pair sometimes haha? Also it does help if you raise with junk and flop a straight or something which i've been lucky enough to do a couple of times

I only 3 bet bluff if the raiser is aggresive but tends to fold to 3 bets. I never do it if I was reraised by a very tight player who is obviously sitting a monster premium hand. Doing that is suicidal to put it gently

Yeah, i know i am an aggressive player but i'm not foolish enough to try anything with a tight player unless i have a monster myself haha, is the small blind the best position to 3bet with since if you call, you are playing the hand out of position? Also, which hands should you just flat with on the small blind, and which should you 3bet?

It's situational. (obv)
First off, are you referring to tournament play or cash game?

Tournament play.

When you have position, the raiser raises too many hands in his position (likely has a weak hand), and has a fold to 3bet of >80%.

Thanks GWU73, i'll keep that in mind