If you want to improve, you need to practice. If you want to do it quickly, you need perfect practice. What is perfect practice. It is practicing very specific aspects of your game with very specific goals.
I'm not a huge fan of drills that you find in most pool books. The "set up this shot and shoot it until you hit it 9 out of 10 times, then set up this shot and shoot it until you hit it 9 out of 10 times" is a very slow and frustrating way to try to get better.
Instead, pick one aspect of your game, like alignment, speed control, building your stroke, whatever. Then find a single drill that works that one part of your game. There are a million possible shots on a pool table, and it will take a long time to learn them all. Why not develop the skills that can be applied to every shot you shoot?
Set a goal for practice. do your practice. Then forget about practice and go play. You can not practice and play at the same time. When you play, you should play well. When you practice, you should practice well. Mixing the two prevents you from focusing on either one. When you try to chase two rabbits, they will both get away.
Steve