There is a game mechanic (arcade version) where you can put yourself into the lower left bounce chamber and wait for the enemies to follow you in. Let them kill you. You will with your next life appear in the normal start place while the enemies are still in the chamber. It is then easy to hold them in. When you get to the higher levels, the bounce bonus will be enough so that you can be killed then get 4 lives back. It is then easy to build up lives and beat the game. Before you do this method, you want to get as many decoys built up first and then burn through them before doing the kill+4 life method. Enjoy!
The game is lots of fun.