Call of Duty 4: Modern Warfare/Multiplayer Strategies

General Tactics
These tactics can be used in almost every type of gameplay:
 * Watch the Radar - It can tell you where the enemies are; this gives you the chance to throw a grenade and prepare yourself or tell you which direction to go in.
 * Call in UAV while Sprinting - This means that you don't have to wait for the animation so you can react more quickly to enemy attacks.
 * Learn the Maps - One of the most important things to do, learn the hiding places and where to fire Airstrikes. This will help you a lot.
 * Stay close to walls - This means the enemy will have more trouble trying to hit you and you will be more camouflaged.
 * Move in the crouch position - This makes you less of a target and people can hear you less.
 * When going into open spaces, sprint - This makes you less of a target and may show you where enemies are. Try not to do this for too long.
 * Aim down your sights - This makes you a lot more accurate.
 * Throw flashes inside closed spaces before you enter
 * Always move to different sniping spots every minute; you're never safe
 * If you earn a helicopter, wait to call it in until you respawn after being killed. Go kamikaze and take out enemies with no regard for your safety and then call it in after you respawn.  If you're careful and let your helicopter do its work, it will often earn you another UAV, airstrike, and heli with very little effort.

Free-for-all

 * Stay on the move constantly - Campers are found and blown up rather quickly in this game mode.
 * Learn to hip fire - SMG's are very efficient in FFA mode for this reason.