Upgrade Complete! Walkthrough

Myself, I used four magnets, five lightning, and three missile launchers... with this configuration, you don't even need to move your ship. BUT, now that I'm just playing for fun, I'll probably try other things.

Get the rocket launchers an lightning things. They are REALLY helpful.

the way i went was
upgrade guns
Magnet to get money
Lighting
Speed
Missiles

that is the best way i went