I look at the number of enemies I have to kill to decide what weapons to use before I start. (keeps up your high score if you don't die) Large number of enemies = fast weak weapons: spread, four homings, lightning, vortex Small numbers = heavy weapons: Energy homers, laser lock, lightning, BFG...
Use BFG's and lightning and energy homers on 29. Lightning first, to weaken the towers (very effective) then use BFGs down a row twice to finish them off. Anything thats almost dead, use energy homers to take down. Once u start destroying towers its not as hard
 "Heavy Weapons"){kind=icon}
 "Endless War 3"){kind=icon}
 "Particles"){kind=icon}