Obvious. Hog the power weapons and always try to flank the enemy. Use right weapons at the right time. ALWAYS have a battle rifle because if you get good you can 5 shot in normal play lists and 4 shot in MLG. I would recommend MLG because your damage is 110%.
Good luck and if you want more help add me my gamertag is PT HYP3RRABB17
Shoot and kill people.
halo 3 odst, unlike halo 3, has no matchmaking, sorry
Unlock achievements or play Matchmaking a lot.
To play on Halo 3 matchmaking you must have a gold xbox live membership and an internet connection to play on matchmaking. If you only have a silver membership it will not let you play matchmaking.
No not unless you were banned from Xbox live all together.
Matchmaking
keep doin matchmaking.
play in matchmaking
Yes. Halo 3 and Halo: Reach both have Matchmaking.
You play a lot of matchmaking games and over time you gain XP and rank up. This requires Xbox Live, if you didn't know. (If you didn't know that, that is very sad)
on the halo 3 main menu go on matchmaking pick a gametype and select start match making
no it will not it will have firefight like a halo version of gears of war 2 horde mode