Really difficult question to answer because of so many variables. Such as; what game, stack size, number of players, position, behaviours, tilt, etc, not to mention the cards.
However, if you’re asking in a more general sense, I’d have to say for me it’s about what information I can get before the flop. Whether it’s at the beginning or the end of the game, I’m constantly trying to build profiles on players the best I can….
Who’s playing the most/fewest
hands?
Who’s folding to big bets?
Who’s a calling machine?
What cards did the PFR or 3BET have at showdown?
Stack sizes.
Irregular playing patterns.
When to pick my spots.
Knowing when to fold.
Really, the list goes on, but that’s just off the top of my head.
Hope this helps.
Keep Studying. Keep Grinding. Have Fun.