So I plan on getting CoD4 either tomorrow or monday... Is there any tips or advice you guys can give me before I depart on my FPS quest?

also, is it really n00by like halo 3? what I mean is, will I have some annoying 12 year old screaming in my ear every other match?

I find that the ratio of children to adults is far less than in Halo 3 because it takes more skill to survive, and being killed every 2 seconds in CoD4 is demoralizing to children.

The only tips I can give you is play the campaign first to get a grip of the controls on at least normal difficulty, use headphones or have surround sound to know where your enemy is, and learn that when you're being shot, to know where your cover is, and hide behind it somehow, even if it's low. Go prone if you're in trouble while behind cover, learn to only fire when you know you can hit what you're aiming at, and keep moving.

You should get a hang of the game quite quickly. I'd start off in FFA myself, so you can learn the layout of the map without any kind of pressure of a goal, plus there won't be any team-stacking, so you'll be matched with people of your skill level.

ok cool. My older brother (he's 20, I'm 18) has been playing since the game came out and now I finally have the money to buy a 360 so I was going to go out to play with him. Do people with perks have a great advantage over new players or is it just a convenience?

It's a great convenience.

For instance, the first moment you begin playing in the multiplayer, you'll already have access to the most powerful weapon in the game: the M-16 and the grenade launcher. One direct hit with the 3 round burst of the M-16 can kill almost anything and the grenade launcher is a 1-hit kill. Perks just make it easier to manage the guns you like.

For instance, I use the M16 alot. I love having a red-dot on it, bandolier (extra ammo, perk 1), stopping power (perk 2), and dead silence (silent footsteps, perk 3) on. It lets me survive for incredibly long periods of time because I can kill instantly and run silently. Without them, I just have to switch weapons with those I find on others after I run out of ammo and be more aware of my surroundings when running.

I'd also suggest finding some videos of really good players in matches and watch how they move. They never leave their backs open by running out in the open, they stick to cover, and run out of sight when shot at. The greatest defense you can have in MP is loss of sight. If you're spotted and you don't have the upper hand, retreat behind something and run away. You'll find someone else to kill. Don't be stubborn, let the kill go.

I was looking at perks and I think this would be a good setup
1 bandolier
2 juggernaut
3 deap impact/steady aim

how do you get perks btw? is it through acheivments or do you buy them with xp points?

You unlock them automatically as you progress through the levels.

Well perks are unlocked through playing automatically. You rank up in levels by getting kills and winning matches.

You start at level 1, and at a certain level, such as level 5, you automatically unlock a perk or weapon. You have to reach around level 45-50 before you unlock the setup I described, and you can only have one perk per slot (no having both deep impact and steady aim in one slot).

Ha, beatcha to it Sereph.