Halo 3 help

Alright
First i suck at the game/semi decent.
What i want to know is how the leveling up system works and if anyone here plays halo 3 often so i can chill with you sometimes.
If you do add infernal entity. Xbox live ftw

Now if anyone can help me get certain achievements and i mean help not just tell me what to do that would be helpful.

I need
mongoose mowdown
Used car salesmen
2nd rank up 1
Two for one

And if you can help then hook me up for CoD and ill be ur buddy der

And for a little teaser of what i can do ask the masterchief

Used car salesmen can be achieved by shooting down a Phantom. This can be done on any difficulty on the level where you have to fight your way through the barracks.

And if done it so many times and i couldnt get the achievement. Iv shot alot of phantoms down

The ranking system works using a combination of Skill Level and XP. You gain one xp for each game you play (except Doublexp Weekends and Ranked Big Team Slayer). You gain one skill every now and then in a RANKED game. (Note you can go down skill from losing games every now and then, and the spaces between each skill as you progress become wider, much like RS Exp).

Enlisted Ranks are ranks without any skill needed. These are: Recruit, Apprentice, Private, Corporal, Sergeant and Gunnery Sergeant. You proceed up these as you get more xp. Note: You dont need any skill for these ranks. You can have these ranks when at 1-9 Skill.

At 10 skill, things change. You become a spartan officer. At 10 Highest skill, you're a Lieutenant. At 20, a Captain. At 30, A Major. At 35, A Commander. At 40, A Colonel. At 45, A Brigadier. At 50, A General.

The type of rank you are varys due to the amount of XP you have. E.g. at 10 Highest skill, you're a Lieutenant, but you can either be a Lieutenant, a Lieutenant Grade 2, a Lieutenant Grade 3, or a First Lieutenant. At 10 High Skill and 70 Exp, you're a Lieutenant; At 85 a Lieutenant grade 2; At 200 a Lieutenant grade 3; At 400 a First Lieutenant.

For a full list of rankings, visit my rank history. If you go over a rank you can see what's required for each one.

My Rank History: http://www.bungie.net/Stats/Halo3/RankHist...yer=ChEYNeY%20C

~Mugger84

Mugger add me tomorrow u seem badass i need help to get my achievements and to level up
Btw do i need to win the game to gain an xp or what ?

Sorry if i seem so nooby im more of a call of duty4 dude

Yeah to get the exp you must win a game. If you leave the game before it ends you lose an exp.

Kero if u know chapp add chappell4444 hes one of the best halo players ive played with.

also add me ive learned from him coocoocajoo420

The game takes practice so thats all you need to win trust me.

Hmmm sounds good ya i just did used car salesmen by shooting down the turret on the phantom.

Two for one
i havent been able to get vallhalla

Mongoose Mowdown
i havent been able to get isolation