I've read a lot of other people's combat strategies and I will admit, those are for braver people. I tend to fight methodically, which often means slow and stealthy. With the practice, I've actually found playing on Heroic Mode now to be easier than the first time I played on Normal. I'm not the best at FPSs (a supreme understatement), so these strategies are really for my brothers and sisters that just don't have the knack for this kind of thing but still want to play.
Snipe with the pistol or rifle, or drop a grenade. A Covenant manning a Shade is a sitting duck, but can be a pain in the butt if ignored during a fire-fight. If you have a Banshee or Scorpian handy, a well placed shot (from the Fuel Rod or main canon r espectively) will flip 'em over. Since only you can right them, this is very handy for tipping the odds in your favor should you have to ditch your prefered ride.