Many encounters become easier when the party begins in useful positions instead of reacting after the fight has already gone wrong.
Read the terrain before acting
Elevation, chokepoints and hazards can change which actions are valuable.
Keep important targets accessible
Position characters so the party can focus dangerous enemies without wasting turns on movement.
Protect fragile or support characters
Keep vulnerable characters far enough from immediate pressure that they can still perform their role.
Change position before changing the whole build
If a fight repeatedly fails, a better starting position may solve more than a complete character rebuild.