Halo 3 is my favorite video game, at least until reach is out.
Keep trying. I have some suggestions.
-Alpha site
-when iron turns un on the bonus round, shoot two fuel rods or rockets in each hole above the elavator shafts.
-the elavator on the ground will store weapons the whole game, juggle some there for use later.
-remember the rockets about the bench on the other side of the map.
-when coming up to chieftans, use one plasma shot and one rocket.
-when coming up on hunters, (hopefully you saved some fuel rods in the elavator) fuel rod them until they die. its usually five shots.
-when mythic turns on, i recommend juggling plasma weapons to your side of the stairs, it helps in the long run. on the first wave of each round, you can spawn kill if you have a hammer. |BEWARE OF CATCH SKULLS|[{only do if you have ALOT of lives}]
thats about it. I got recon, if you find the right people, you can too.