Get your bonus multipliers by hitting drop targets in order, that is really it. Bale out shots are the left rollovers and the middle spinner.

Hit the drop targets in order of white, yellow, blue, and red to get the respective bonus multipliers. Note that you are able to hit targets out of order, but you will not get the bonus multipliers till the previous drop targets are cleared.

Other than drop targets, you can also get bonuses in 2 ways. The first way is to hit the 4 rollovers on the left side of the playfield to advance the bonus indicator in the middle of the playfield. The second way is to hit the spinner in the middle of the playfield to advance the bonus indicator. You need to advance the bonus indicator 5 times to get a bonus.