My biggest tip for this game is to make heavy use of the guard command. You can aim your reticle at a spot of ground and give the guard order via the radial menu and tell your star to "guard" that spot. They spread into a grid formation and will just engage whatever comes at them. I realized before I did this, I was always on-point and frequently taking the most damage if I stuck to "follow my lead" all the time. Also, the starmates would keep crashing into me or each other during "follow my lead" mode. Whereas with the guard order they mostly stuck to the same spot a short distance apart from each other, and that cut down on the friendly fire and crashing around.
Many times using this tactic, it allowed me to move back or off to one side, keeping a clear line of fire and contribute to the shooting, but also just monitor the big picture a little more. It gave me the excess mental brain space I needed to be more of a leader of the star and not just it's pointman.
I could even keep my unit somewhat mobile, changing the guard command location periodically. Particularly if my star was mostly of about the same speed, by accident, they would move like a box-shaped unit (more or less, it isn't perfect). So it felt more like moving a unit of 'mechs around the battlefield than trying to position individuals using the battlegrid or any other method.
I apply this once I realize red contacts are appearing ahead of us. Since most of the time the enemy AI just comes at you, it works pretty well for most situations this game presents you with.
I only occasionally would use the specific "attack target" command. Most of the time I'd let the starmates pick their targets. Unless I saw a particularly nasty threat I wanted deleted immediately. Or something mission-critical.
For choice of guard location, I've tried it both ways. Tucking my unit into areas where they have cover from long range fire, and positioning them on high ground in the open with good long range sight lines. High ground in the open tended to work better more of the time because it provided more opportunity to make use of long range weapons and do a lot of damage before it turned into a close range brawl, which was when the AI seemed to be the most effective at doing a lot of damage. But I guess that also depends on what 'mechs you are using and how they are outfitted. But the longer range of Clan weapons is an advantage to keep in mind.
Final semi-related tip. Make use of water wherever you can. The heat dissipation bonus of standing in water is awesome. It saved my butt a few times, most notably one mission where I lost every 'mech in my star but my own. I was in a Warhawk. I stuck to walking around in water and engaging the incoming targets one by one with my Warhawk until I had single-handedly deleted about 8 'mechs with nearly constant PPC fire and the mission ended successfully. It was one of my proudest individual moments in the game. I wouldn't have been able to keep up that pace of fire without the added bonus of water cooling.
