4bet the lagtards in spots where they seem to be most loosely 3betting, i.e. OTB or from the blinds. Do it with hands that have some blockers, e.g. KJ, KQ, AQ/AJ, QJ for 4bet/fold candidates

vs. nits just snap fold to their 3bets unless you think they are doing it in an obvious spot and their % is at least 4%, then 4bet them with some blockers.

Flatting 3bets is mostly gross, I'd rather flat AA/KK vs someone spewy