in a pot with many limpers move in with any two cards. high chances that limpers won’t call against a bit bet (unless trapping), but look around for signs of stregth (pokets eg. AA/KK, or QQ/JJ/TT).
preflop if raiser a caller, move all in against everyone if last to act. raiser will get scared about two things, the massive raise he’s facing and the caller behind him. this is not an auto play, assess the table before executing it.
maintain stack size throughout the tournament, by repeated aggressive stealing from timid players or aggressive ones (let go against those if too hot). by try in both cases.