If you’re having trouble getting past a certain level, don’t be afraid to fire off shots indiscriminately. Though it will negatively affect your score, sometimes flinging a ball forcefully and somewhat randomly will end in a result you didn’t expect -- giving you fresh ideas for how to make a more accurate shot next time.
Some baskets can be made much more easily if you adjust the starting position of your shot. Don’t be afraid to adjust before you shoot.
When playing 1 on 1, try to knock your opponents balls into their own basket. You get double points, plus it will make your opponent angry.