I like the quote" If you can't find the fish at the table then you are the fish"
Betting patterns are the 1st sign, good players know when to speed up and slow down. Good players also know when to lay down hands or call for pot odds
as opposed to calling every bet until showdown. You are never pot commited, lose the battle to win the war. If a guy bluffs you out of the pot, don't go on tilt, just remember the history of the hand and use it against them later with a check-raise or a re-raise.