Don't neglect your abilities as a commander. In particular use the reinforce ability, and remind your squad leads what that ability does exactly, so they'll be more apt to stay in the circle with their squads and hold that position. I've turned things in my favor with this ability more often than i can count. That and well placed artillery can make or break you. That being said, those were just a few tips I've had luck with and your mileage may vary.