Watch out for the turn buttons. Once they turn red it is swipe time since enemy is about to start shooting at you. Swipe in any and every possible direction to dodge the bullets.
Always scan the area for enemies and a safe spot, a spot you can get behind and shoot at enemies without worrying you'll get a bullet or two from them.
Pinch to zoom the area of interest. Chances are you'll get a hold of a weak spot that can help you earn bonus points.