Before playing one of the games, repeatedly press C-Right. You can get up to 99 continues.
In level 1, allow all the enemies to get into formation and note the bottom left bee. Kill all of the other enemies except for that bee. When just that bee remains, place your ship in the lower right corner. Allow him to fly around and attempt to attack your ship. After one pass with him not firing, allow him to pass again. If he is still not firing, shoot him during this second pass. This will take approximately 15 minutes. Doing this will disarm the enemies for the remainder of the game.
Shoot one of the green ships on the top row to turn it blue. When one of them dives alone, avoid its shots. Intentionally allow your fighter to be captured by its tractor beam. With your next ship, wait until the joined ships to dive. Shoot the alien while carefully avoiding your captured fighter. You will have a double fighter with twice the firepower.