Not much to say for a 'strategy' - a lot of evasive maneuver and taking cover, plus a small portion of luck, perhaps? ;) I picked out the Scouts first cuz their speed and bullet spraying make their attacks harder to evade than those of the other bigger enemies. And I tried to minimize the flank attacks by enemies - in Trial by Fire difficulty, those are pretty lethal. Using the front-shield saved my life so many times, of course.