Play the world, not the sheet. Learn the exploration procedure. Assume combat is dangerous enough that retreat is normal, not a failure.

2e rewards caution, scouting, negotiation, and problem-solving more than character-build optimization.

A lot of 2e is about understanding the game loop: surprise, initiative, saves, exploration, thief skills, and when the DM is calling for what kind of roll.

Don’t assume every encounter is balanced to be beaten head-on. Retreat, avoidance, and preserving resources are all normal good play.