Quoted from pinmister:I feel like I need to go back to school and skip practice. I think I could improve my overall scores by really learning the rule sets and strategies better for each game. I will make this a goal this year
Top competitors often have good rules knowledge but you can usually find enough in a few minutes at pintips.net and a few other places.
Practice will teach you when to dead bounce, drop catch, or live catch. It will teach you how the speed of a ball traveling through in in-lane will affect your accuracy. When to nudge BEFORE the ball ever has the opportunity to become uncontrollable. How to recover from a missed shot and what to shoot to keep a miss from turning into a drain.
If you're (un?)lucky, along the way you'll notice the limitations of competitive pinball's ranking system so you'll become an organizer and try to run fun events for a wide variety of skill levels. Then you'll become a world-class pinball stream commentator, and finally graduate to Pinside cynic.