Check it out... I've got the lowdown on the greatest entertainment release in the history of Earth. Here are some good tips on Halo 3 campaign and multiplayer.
CAMPAIGN TIPS:
-to get invincibility, kill a brute chieftain from a distance with a head shot weapon so he doesn't see you. Run to his dead body and pick up the invincibility.
-When you have a Spartan Laser, use four shots (it only has five) on high value targets such as wraiths, turrets, and chieftains, then give the Laser with one shot left to a marine and protect him. He will have infinite ammo for it and take out vehicles for you the rest of the level.
-A great combo is dual-wield a Spiker with a Plasma Rifle. Also, dual Spikers is good.
-Another use for the Deployable cover is to block off a small passageway, to stop enemies that can overwhelm you like Flood or Drones.
-Spike grenades will stick to enemies, but unlike plasma grenades will also stick onto walls, ceilings, etc.
-Flamethrowers will easily dispatch pure form Flood, but will only set the combat forms on fire, while they continue to run at you.
MULTIPLAYER TIPS:
-The Hornet never appears standard on a map. Use custom game settings or Forge to bring it in.
-When playing Capture the Flag, bring two people over to the other base on a Mongoose, have the passenger jump off and throw a flare down to temporarily blind the opponents, and run out with the flag. Back up the Mongoose with a Ghost or Prowler perhaps.
-The Spartan Laser is the ultimate anti-air weapon, aside from the Missile Pod. The Missile Pod is a portable turret, and as such will slow you down, and be hard to find. The Rocket Launcher does not lock on any more.
-The Needler is no longer dual-wieldable, but it is more powerful.
-Use trip mines against opponents, vehicles, and plant on spawn points.
Any HALO 3 questions? The Twilighter Zone will answer them.