Banked shots are more difficult to make because the line doesn't show you where a ball will bounce after it hits a side wall, but such shots are also the key to scoring great combos.
Combos are the secret to a high score. If you get enough combos built up, the value of each new combo doubles for a brief period.
Don't worry if you start out with a few small combos, to bring spiders out and help improve your score. You can worry about the large ones later, as you have more multipliers in place.