The key to the game is the firing just put a bunch of light turrets in a cluster for a crazy shotgun effect for cheap man i hate the ammo becuase when i get frustrated with the 6th wave i just go fully auto and spray everything with lasers!Keys to success
.have a good firing sights make sure all your turrets dont hit the planet
.only go crazy fully auto if you have to and theres like 10 blue thingies
.conserve ammo short accurate burst should be sufficiant to take down any thing!
.also use fully auto if you want to make all your stuff to explode and then destroy all on map!