What exactly are you trying to figure out?
Best way I get points is to just hit things consecutively. For example, if you're trying to aim for a pot and/or the gold disc and miss, you'll have to start over. So if the targets you were shooting went up to 30 X 12...you would be missing out on 30 X 13...which is a lot of points.
And for the last level, all you have to do is shoot the reddish orange spots on his feet, and then the back of his head.