In any of the Single-Player modes a good strategy to have a better chance of surviving a long battle is to have a blaster rifle and Health Boost 2 or 3 equipped. The blaster rifle has a large magazine capacity and good firing rate and the Health Boost will add a multiplier to your health bar. The best use of the blaster rifle is in ground engagements where it's accuracy and medium range will allow you to weaken an enemy from a distance and finish them off as they get close.
Space: Start off in Capital Ship, lay an Auto-Turret, fly into space, come back into Capital Ship, lay another Auto-Turret, etc. Ground: Start off on ground, lay an Auto-Turret, fly into space, come back to ground, lay anothe Auto-Turret, etc.