Halo 3 Hints

When fighting the flood, if you carefully shoot their arms off without killing them, they will follow you around harmlessly without killing you. Its kinda like having a pet flood. USE THEM AS DECOYS :D

In forge go to sandtrap were there are elaphant (2) turn to the moniter and buy a tank and try pushing it not to close.Once you flip it there will be a note on the upper side of the screen.

There will be a dead marine that has a teddy bear in his hand on the first level(Siera117).It is near the checkpoint called Charlie Foxtrot.Also I did this on legendary mode so I think its only on Legendary mode.

start at metropolis level and go to the door with the blinking light and jump on the look on your right and jump on that light and crouch jump on the roof then keep moving and then you will find it

Notice how some of the human guns kinda look like guns in real life. Here are the ones I know:
Magnum-USP .45
SMG- Mini Mac 10
Battle Rifle- Famas G2
Sniper Rifle- Barrett M82A1
Shotgun: Remington 870

in forge create a computer and watch a brownish screen the rest is for you to find out???