Here's an example of a typical range
Here's an example of a typical range you may flat call within a lot of different situations. To improve your results, stop flatting 22–66 from the blinds to a steal attempt if you're doing it now, unless you're nice and deep and against a really weak opponent. Don't flat off suited hands in position against strong opponents. Even with position, if they are decently good it's going to be hard to play them profitably unless you have some very specific read. Don't flat AT–A9, KT––KJ, QT–QJ type hands from early and middle positions. You'll often be dominated and you'll still have a lot of players left to act. Don't flat suited connectors out of the blinds unless there are really weak players in the pot with you that have decent stack sizes.
Take some of that very same hand range
Take some of that very same hand range and turn many of them into 3bet bluffs, or in some case 3-bets for value against certain opponents when in position. 3-bet or fold 22– 66 from steal attempts when in the blinds. 3-bet or fold AT–A9, KT–KJ, QT–QJ type hands in latter middle position instead of flatting. Experiment with different hand ranges based on the stakes you're playing. In some games you can 3-bet KQo for value and still get calls from worse hands, and some games you can't.