1. You need deepish stacks (a, because you want to get paid when you hit and b you want to be able to bluff and get away from a hand postflop)
2. You must either be against a villian where, if you hit you will be playing for stacks, not half stacks!
3. You can play if you think that your villian will fold if he misses postflop. Sop either you want a very low c-bet %, so if he checks you bet and he folds OR a very high c-bet frequency, he c-bets a lot of air you re-raise he folds.
With the villian who you play for stacks with, you need ma MW pot usually to get teh right price to call preflop (you also need position!)
With the villian who can be outplayed postflop, you want a HU pot because you dont want to be bluff raising a MW pot.
When you play a MW pot against weak players, they are playing fit or fold which means they will not be playing for big stacks without a big hand, so in this pot you do not have implied odds
, therefore 3bet in position or fold. You will not get to play for stacks postflop enough to justify the call.
So base implied odds on the first raiser, he is the one who potentially has the strong hands, not the 5 callers after.
As an openers range widens with position, against CO or Btn opener, 3bet these hands, you are looking to win preflop, but have a hand that plays of postflop if he calls.
The biggest mistake you can make in poker is constantly thinking hands have huge implied odds. Most of the time hands miss the flop, and the times that they do, usually people do not want to play for stacks, therefore you are instead looking for situations where a raise can win the pot immediately, but if that dosent work and it is called, you have a hand that allows you to play back at some pots postflop.
The only exception to this is where a villain (usually UTG) has an extremely tight range and will felt with a lot of his range, here you just need a decent price to call.
So consider flatting hands like AJs in position and 3betting hands like 78s in position.
AJs will play better postflop than 78s so you 3bet 78s if you think villian s range is wide enough that he folds to 3bets a lot. If he calls, all is not lost, you may hit 2 pair, have some kind of straight draw you can semibluff raise or have a flush draw etc.
AJs on the other hand can be flatted because it plays so much better postflop that here we want to flat and play our position
With regards to playing incorrectly, if you 3bet a player with a narrow range, he will likely 4bet and SC dont fair well in 4-bet pots. Against a player with a wide range, do not flat, he will not pay you off enough when you hit, but will fold a lot if you 3-bet.