Here's an assortment of hints-

Rockets work well on a cluster of people.

Take advantage of traps and learn how to avoid them.

In the first space level, the platform that moves up and down changes you into a plane breifly if you launch off it.

If people are on your tail and you have cluster bombs, use them.

If someone's on your tail, and you have a close-range weapon(axe, bat, chainsaw, boxing gloves, etc.), hit the brakes, turn around, and hit them with it.

Learn where shotcuts are and when to use them.

That's all I have to say.