Here are some pointers:
- when hit with gun (like those on a vehicle with upgrade), you can't jump. so you need to avoid being hit by hiding or standing right between the bullet stream to be able to jump
- get some strong guns (like rocket launcher, flamethrower or electrogun). But each has it's own advantage and disadvantage. for example, the flamethrower can be avoided by jumping on time. it also has a short range. however there is a small trick to increase the distance by leaning on a car.
- surprise is important in this game. so for example if you got a oil slick on your car, you don't need to use it directly but try to trigger the enemy in following you and when close to the water drop the oil. which brings on a good tip, never ride exactly behind a enemy, he could have mines.
- some cars can handle two rocket blasts others not. keep that in mind when you know that the enemy is in an area where he can get rockets.
- when being attacked I often use the walk back and left or right tactic. so you keep a good distance and move left or right to avoid rockets/bullets.
- the fist looks weak but it can actually kill and be nice surprise. for example, when you have electro fingers, just try to hit enemy and you kill him. or when he enters/exit a car and you are close by, you can also kill the enemy (takes practice this one). or when the enemy jumps after you over a car you can stop and wait till he lands and hit him with the fist (following with a shotgun shot is deathly)
- use other objects to kill enemy, for example shoot cars that he might pass by. or shoot on the wall (with rocket) can also trigger to explode the enemy car or blast him on the floor.
etc... I can go on for a while...