There are many types of Grunts. Grunts stand 5 in off the ground and are easy to kill. It takes 1 melee attack to kill a orange grunt, and two melee attacks to kill red ones, so if you see a pack of orange grunts, run in and melee attack them, saving ammo. Beware of the black grunts. The black grunts always carry fuel rod guns that explode after you kill them.

The Elites

The elites are one of the strongest covenants in the game. They resemble people but are different colors. The weapons they carry are the Plasma Rifle, Needler, and the dreaded Plasma Sword. The Plasma Sword can kill the master chief in 1-2 blows. Throw  a plasma grenade at them to save ammunition. Be careful after you throw it on them, because you will have to run because they may run at you before it explodes causing your death. Watch out for Elites in close combat, because they will melee attack you.

The Hunters

Hunters are deadly aliens. They use a Fuel Rod Gun; the gun on the banshee. The best place to shoot them is in the back or in the neck in their orange flesh. One shot with the M6D pistol will put them down in the orange spots. A good tactic is to let them charge you, side step and shoot them in the orange flesh with the pistol. Hunter also run after you and hit you with their shield. The hunters fuel rod gun does not blow up like the black grunts, but you cant get their gun. After you kill a hunter and go up to it and look down at it, it will have orange blood, the color of their weak spots.

The Jackals

A jackal is an alien with a strong shield that covers most of the body. If you want to kill a jackal, there is a white hole in the middle of the jackals shield. If you throw a grenade at one, it will bounce off due to its shield. Do not throw a plasma grenade at the shield either, because it will bounce off. The other thing that you can do is melee attack it and it will die. The plasma pistol is another good gun against the Jackal. If you overcharge the gun and shoot the jackal, it will disintegrate its shield. Then shoot it and it will have no chance against you.