A missed shot is useful feedback when you can tell whether the problem was direction, strength or a rebound off a wall.
Read the course before shooting
Open Mini Golf and check the aiming controls. Trace a direct route to the hole, then notice any wall or obstacle that interrupts it. If a bank shot is needed, picture the incoming and outgoing directions at the wall. Use that as a starting estimate; the game's physics determine the actual bounce.
Change one part of the shot
Keep your direction steady while adjusting power, or keep power similar while adjusting aim. Notice where the ball stops instead of immediately firing again. When a direct shot is risky, consider a safer position for the next shot. A controlled approach can be more satisfying than repeatedly chasing a hole-in-one.