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.
Like Grunts, Jackals are best dealt with with a smack in the face. But in a long range fire-fight, I like to over-power their shields using Plasma Pistols or Plasma Rifles. Needler is a waste of time and using ballistic weapons short of the rocket launc her aren't worth the ammo. They also don't run very fast, so grenades are effective.