What is this guide for?

Call of Duty 4: Modern Warfare is a very popular game with some really fast paced action. You will kill a lot and you will die a lot but in the end it all comes down to who is the best player and this guide is all about the being the best. To achieve greatness you will need to exploit some of the games most powerful weapons and perks and mix in some strategies. No one remembers second best so follow this guide and be prepared to be called a PRO or a HAXXOR by the people you just OWNED!

The Basic Configuration

First of all, Lets try to get rid of some Lag. There is nothing as frustrating as Lag when it comes to playing games. So unless you have a very powerful system I suggest you turn off the shadow settings since the difference is barely noticable and you gain a good deal of FPS by turning it off. Adjust the other settings if needed for better performance.
Call of Duty 4 is a great looking game but that pales in comparison to the game play it has to offer. So adjust the setting for the best performance.

I will not teach you what button is used to move,run and shoot (learn that yourself) but you can adjust the keyboard layout and mouse settings to your liking. If you have a spare button in your mouse that you can easily access then I suggest you add your "melee attack" button there for quick access to knife the enemy if ever you bump into each other. Also designate a mouse button for your grenades because you will be spamming them a lot.
I use a Logitech MX518 mouse and put my "melee" attack" on my BACK thumb button and my "push to talk" on my FORWARD thumb button and my 'throw frag grenade" on my MOUSE 3 button.

The Killer Setup

In Call of Duty 4, you have access to different weapons ranging from assault rifles, light machine guns, sub machine guns, sniper rifles, shotguns and pistols. All have their strength and weakness. But you must know that in Call of Duty 4 it does not take a million rounds to kill someone. The hit damage in this game is so high that a pistol can kill 2-3 people in one clip. Any weapon can easily put an enemy to the ground and he will curse you as he watches a replay of him getting owned. The secret to a kill is accuracy and speed. Accuracy doesn't mean you have to aim for the head all the time or zoom in for the perfect shot. In Call of Duty 4 the spray and pray effect is actually very effective as long as you make sure you the target is in the center of your cursor. You would even be surprise to shoot him in the head with out even trying. Speed is the what makes you win head on gun fights with an opponent. A typical player would have to zoom in first and set up his aim before they start firing away and that takes time off their part as to where a good player can fire off his hip and kill an opponent before they even gets a chance to aim. This is where your gun and perks class becomes an important asset to your success.

this is my KILLER setup. MP5(red dot optional), any pistol will do but if you want the best pistol then take the Desert Eagle.

Why the MP5?
PROS: This is the ultimate gun in CoD4. It is light which means you have greater Mobility and can run for cover from enemy fire more quickly. Has a quick reload time. Great Accuracy which means no more need to zoom in. An already high Damage output which can be even increased with the Stopping Power perk. Great Fire Rate which can be increased with the Double Tap perk.

CONS: The only weaknesses of this gun is the Range but thats not a problem in Call of Duty 4 as the maps are tiny and have small corridors with an exemption of a few maps. Also the ammo count of the MP5 is a little low but you can always find ammo anywhere since this gun is quite popular and can be found all over the grounds.

Why not the P90?

I find the P90 to be very similar to the MP5. The P90 has a better Fire Rate and more ammo than the MP5 but has lesser Damage output. The P90 is actually a better gun if your going to face an opponent in a 1 on 1 battle. But Call of Duty 4 is a team based multiplayer game. You will usually be facing hordes of enemies in every gunfight you encounter. That's where the MP5 is better due to more damage output. With more Damage you take lesser time focusing your fire on one opponent before you face the other opponents. Also if you use a the Double Tap perk with the MP5 you virtually get a P90 with more Damage and better Range.

The Perks Setup

Perks:
Fragx3 - Great for spamming (especially in maps like Bog, Wet Work and Shipment). Your objective is to kill as much as you can as fast as you can. If you see a red dot in your UAV then throw a few grenades in that direction and you get a good chance of killing that person. Throw your grenades higher for more distance.
or
Bandolier - If you find yourself running out of ammo quick because of all that spray and pray fire then take this perk. This perk is also great for the Overgrown map where it is easier for opponents to avoid grenade spams and you don't need to keep on looking for guns and ammo hidden in the grass fields when out of ammo.

Stopping Power - This will increase the damage of your MP5 and this perk is available at the beginning. You can replace this with the *Double Tap perk but you run out of bullets quit faster and you wont find much difference in your damage output with the Stopping Power perk plus you will have more bullets to spare for the rest of your victims in the vicinity. Besides the MP5 already has a great Fire Rate so I will stick with Stopping Power perk.
or
*Double Tap - Doubles your rate of fire meaning for every single hit you make you get double the output. You also get a slight better chance of a head shot as your bullets cover more area of trajectory. Great for 1 on 1 battles but you tend to loose ammo quicker

Martydom - Everyones most hated perk. Great for small confined maps. You want revenge on your killer? This is how you do it. Free kills with Zero effort. I replace this with the *Extreme Condition perk on bigger maps (Overgrown, Ambush) because there is more room for your opponents to sprint away.
or
*Extreme Condition - Sprint till your hearts drop. Great for chasing down victims around big maps. The MP5's only weakness is the range. In small maps this is not a problem as most battles are in very close proximity but for larger, wide spaced maps you need to close the gap with your opponent to be more effective. Also great for running away from enemy fire and martydom.