You can rack up sick scores by using point-boosting weapons for long periods of time against enemies with limited hitboxes. Level 2's sub-boss is a good place to do it... using the rocket glove weapon especially. Also, the lighting weapon against the rocks in level 4 after the sub-boss gives you sick amounts of extra points. For some reason, they are classified as enemies by the game engine. Plus, any boss that spams minions can be farmed for lots of extra points, such as level 3's sub-boss and level 5's form 2 boss.