Select a troop type, then deploy them outside of the red region in different places. Maximize Energus and Crystal Depots as soon as possible so you can refill supplies easier.
You have a choice between Marine, Blazer, Sniper, Shock Trooper, Engineer, Ninja, Drone, Grimlock, Sweeper, Deathbomber, Bruticon, and God, listed in ascending order of cost and power.
Build military buildings conservatively and balance them with resource-producing facilities.
When defending, place barriers, gun turrets, neutron cannons, shock turrets, and laser turrets as long-range deterrents. Also use cheaper defenses such as shock mines, claymores, M1s, and AA mines in larger numbers.