well, first to survive you need to bulid alot of gun turets but do not bulid any factorys! then bulid a outpost and exchange gunturets for rocket turets.(you need alot of turets to risist a big atack :)) then bulid a heavy factory, and bulid a second harvestor. (here i don't menchon the wichamacolet energy things because you need to bulid them only when you have bulid the wall of gun turets.)