Sit Comfortably
Find a good chair to sit in so that you can have your elbows resting on something. This will help you to keep your crossbow level and steady. From this steady stance, it will be easier for you to keep an eye on the whole screen, and you quickly can move your crosshairs around the screen.
Watch for the Signs.
The best way to rack up high scores in this game is to attack your enemies quickly and accurately. This speed and accuracy is especially important because some targets only appear for a short time. In fact, if you need to repeat a level to get a better score, remember where enemies appeared and have your crosshairs ready and waiting for them.
Exploding Bolts
Whenever you have a chance to use exploding bolts, you take out a lot of enemies when they gather together in one area. Target and then blast the group of them together once you get this power-up. However, when you're using these exploding bolts be careful to not hit targets like cuccos that will actually lower your score. You can use exploding bolts at any time just by holding down the "B" button until your crosshairs flash; then, just release the "B" button to fire.
Experiment
Sometimes, even if something is not an enemy like a stalfos or redead, shoot to earn more points. For example, if you shoot a floating rupee, then you will get bonus points. But don't shoot cuccos or other living, non-enemy characters, since doing so will cost you points.
Shoot Green Enemies
If you see an enemy with a green sheen or glow, then shoot him. Hitting these enemies will give you 100 automatic crossbow bolts. These bolts are incredibly useful for getting and keeping combos or just for launching last-ditch efforts to clear the targets from a level.