Pinball is no different than any other sport(using that word loosely in every sense) in that it requires proper technique, good fundamentals, and practice. If you want to improve, the practice has to be based on that proper technique and not just batting the ball around.

Casual players can sometimes score pretty well just on their natural ability to keep the ball in play and make a few shots. However, a person who has learned the skills of trapping, catching, passing(both dead and live), and especially nudging will always prevail in the end. Making shots will come with practice, some are better than others at the beginning but it can definitely be taught.

You need to buy a machine so that you can play on a daily basis. By just playing a few games on the weekend, you will never be that good.