Hop to New Plane : If your plane becomes damaged, you don't need to waste a parachute to reach the ground for a replacement. You can jump to a new plane by simply flying very close, usually right under or on top of your plane and pressing the jump button. If the other plane is in just the right spot, you'll make it, but otherwise you'll fall.
Destroy UFOs the Easy Way : When you reach the UFO wave of the battle you're in, take your plane down as close to the ground as you can without crashing. Chances are, thanks to the circular pattern of their flight, the UFOs will arc over you and smash themselves into the ground.
Score Big Points : While on the ground, instead of climbing right onto your replacement plane, jump over it. For each time you do this, you'll score 1,000 points. As long as you're careful, you can get a lot of points this way.
Enemy Ran Away!! : After destroying 20 aircraft in a wave, the enemy retreats and you are awarded with 20,000 points and a free parachute!