While playing a "Target Shooting" level, keep on the lookout for scarecrows. Once one is found, shoot the torso of the scarecrow 8 times. The head will inflate, allowing you to shoot it for 1000 points. Do this with the two scarecrows in the level (the second one will only appear if the first has already been shot), and instead of taking you to the default third area, the game will bring you to an alternative area, with more gold targets.
Earn the following medals by getting the required amount of points for each stage.
To gain some extra points, shoot the doors on different buildings. Balloons will appear which you can shoot for 100 points each.
After shooting objects, they sometimes leave a gold coin. Shoot it immediately since its value depreciates as it floats down.
When you find a scarecrow, shoot it at the chest for 10 consecutive times then once in the head. You'll get 3000 points if done successfully.
Completing a stage without ever missing will reward you with a bonus Tri-Force worth 5000 points.