Halo- tips and tricks

I have some very helpful tips on how to beat halo 2, 3, and reach game on any difficulty.
The two gun you want at all times are 1. a plasma pistol and 2. a battle rifle (or DMR for halo reach).
tricks on how to kill all enemys
grunt- aim for the head for one shot kill
jackel with shield (this one takes time to master).- Shoot the jackels hand that is sticking out from his shield, the jackel should then turn and grunt in pain then you have a clear shot for the head to kill him.
skrimish- aim for the head (be quick to shoot)
elite, all types- charge the plasma pistol, shoot it at the elite, that will bring the elites shields down and then pull out your DMR/ battle rifle and shoot them in the head.
Brutes with with shields- same as elites
brutes- shoot there head repeatedly until they die
enemies in vehicles- charge your plasma pistol and shoot the vehicle so it is disabled then get onto the vehicle and melee until enemies death.