I was looking for the BXR tactic, and I came across a few tips from GainedTheLead.com:
1. Face the front of a Ghost. Now move to the right side of the machine where you will find a circular "power source". Just a few shots with any weapon will bring the Ghost down when hitting this weak spot. One shot from a Sniper Rifle will blow the Ghost apart.
2. When approaching someone who has the Energy Sword, wait until right before you think they will lunge at you - and then duck. Very often the attacking player will lunge right over top of you. If you are swordless, this will give you a chance to turn around and finish your shooting. If you also have an Energy Sword, remain ducked as the person lunges at you and then press the right trigger button and lunge at the opponent. This should increase your success.
3. Surround sound speakers are a notable advantage when playing Halo 2. You will actually hear explosions, gunfire and even footsteps from the direction that they are taking place. Imagine the advantage of suddenly being shot and hearing the direction the shot came from. Imagine hearing the boom of a sniper rifle and knowing the general direction from which the shot was fired. Imagine your fear as you hear the sudden twang of a energy sword unsheathed directly behind you...
I didn't know that you could kill the Ghost so easily if you knew where to attack it. Also, I didn't realize surround sound could be so clutch! Man, when I move out, get a monster TV wtih surround sound, I'm going to fucking own everyone!