General tips for everyday soldiers:Beginner Tips - Use M16+red dot sight+stopping power. Usually kills in one pull of the trigger. If you're new, it's imperative that you learn the maps. You'll want to take note of key hot spots, side paths, and sniping positions.
Try not to hide behind cars, as they can explode from gunfire/grenades. ALWAYS, ALWAYS check your corners. Flank enemy positions every opportunity you can.
Once you get to level 25, you'll unlock the G3. Practice with that and the sniper rifles, and you'll most likely be able to dominate with any other weapon. Use the red dot sight with pretty much every weapon. Use both types of grenades that you have (special and frags). Get into the habit of aiming down the sights, all the time.
1.) Start a private match by yourself and learn each map.
2.) Always crouch when moving in buildings. (You make less noise that way when not using Dead Silence.) When in the open sprint for cover.
3.) When enemy helicopters come hug the wall and pray or run for the nearest building WITH a roof. (Same for airstrikes. (At least that's what I do.))
4.) Pick which gun/perks work best for you and your playing style. (Like me, Snipewhore, so I use a Barrett 50 cal. with some claymores, UAV Jammer and iron lungs
5.) Try playing that training part in the first level a few times to get better acclimated to the controls/'nade handling. (Or try to beat IW's 15 second record. I beat it by the skin of my teeth with 14.98 secs.)
Movement - Always try to keep on the move, moving from 1 position to another. Be aware of your surroundings. Your spatial awareness has to be good for veteran and especially if you play online. If you move out in the open, try to plan in advance positions where you are going to run to next for cover, such as behind a wall, so if the enemy suddenly appears you have set places in your mind you can use for cover.Plan a few alternate cover positions in case you cant reach 1 in time. If you are behind a wall or other such cover, and you appear from it and snipe at the enemy, crawl back down and move to another position. that way you wont be predictably appearing up from the same position which would make you a much easier target.
Be Aware - It's simple. Always glance at your radar when you can. Then listen for footsteps and judge where an enemy will be. Look at where your teammates are on the radar. Those areas are much less likely to have enemies. Always try to get to know the map well enough to know where an enemy might be coming from. Predict where enemies will be. Always be ready for an enemy around every corner...because as you know, it is very easy to hide with UAV jammer and a silenced weapon.
I dont know what it is about the game, or maps, but everyone always goes ramboing. these people, are in fact idiots. look out for long grass, tunnels, like on pipework, high rises, bottlenecks, anything you can multi-K or nade or spam to bump up kills. dont run at them screaming something about getting to the chopper all guns ablaze. i garauntee, death will be the only outcome.
If you hear a grenade drop, slow down what you're doing until you hear it explode. No reason to run right into a freshly thrown grenade.
Flaming cars will explode with a blast radius of almost double that of a C4.
If you see a C4, don't just run by it, chances are that the enemy is waiting for you to walk by.
Airstrike? Predict enemy movement. - Before dropping an airstrike, try to narrow down the movement of the enemy players. When you launch the airstrike, don't launch it exactly in the center of many red dots on the radar, instead, look at the map, study it and predict exactly where that all those enemies will be when that air strike hits. It takes about two seconds for the air strike to start kicking in, so enemies could easily dodge it if you launch it in a predictable area. Instead determine if the area of the red dots is an open area, is it? Good, now determine if the area is more of a camping zone (or a choke area) or an area where the enemy is moving through. Now predict where the enemy will be in the next few seconds. You can now launch the airstrike. This is how to rack up many kills with it.
Shoot that heli - Remember to shoot the helicopter. Even regular guns are effective against it. While playing online, I've noticed most of the time the team ignores the heli and lets it destroy people on their team. This is a very bad strategy. Why? Well while you ignore the heli, it takes out say, 5 of your teammates. Now the guy who called the heli could have already died and respawned. Now imagine he got himself a kill, the heli gets 6 or more and now the guy has another heli at his disposal. The second heli comes, and once more you don't shoot it. The guy racks up another 7 kill streak, and guess what? Yup. He has yet another heli. Now you are getting your ass handed to you every time you respawn, and all this because you didnt want to waste a clip (or a lot less if more people shoot at it) on the heli.
Aiming Tips:#1. Shoot the enemy in the body/chest and then in the head to kill him because, for most guns, even with stopping power it takes 2 bullets to kill, even if both land in the head.#2. Aim for the tip/middle of the opponents head to land a headshot. This is due to the scope being mounted on TOP of the rifle, thus leading to a small bullet displacement that increases as the distance increases. At short ranges the bullet displacement maybe only 1 cm, but as the enemy get's farther away, the greater the bullet displacement becomes. (For example, it may hit them in the neck, instead of the head.) If you aim at the middle of that head or at the tip, there is more chance of the bullet hitting exactly where you want it. It works, 90% of the time.
Shooting Tips:Another great CoD4 (thanks for this one scarface) tip is, when firing any of the weapons (assault rifles, sub machine guns such as the mp5) at a distance, always try to fire single controlled shots (to avoid recoil which will just throw your aim off), just move the cross hair in a smooth motion covering any area where you think the enemy might appear.
Non-Headshot snipers: If you find it hard to get headshots with a sniper, use the M40A3 or R700 and use the stopping power and deep impact perks, you will almost always get a 1-hit kill when shooting the torso ( deep impact is for shooting other snipers hiding everything but there weapon behind a wall)
How to tell if someone has Juggernaut - When you fire at someone and you see a red cross, it means they are using the juggernaut perk.
MP5 Main Weapon CoD4 Tip - If you are using an MP5 as a main weapon, use an M9 as your pistol, it uses the same bullets as the mp5 so it's spare bullets act as a poor man's bandolier for your mp5. Always pick pistols with the same type of ammo as your main weapon for more ammo for your main weapon. (Scarface)
Slow down - Don't always run out and think you're Rambo. This is why a lot of people are horrible at this game (joe). Other than that, have quick reflexes, think before you move into an area where there are a lot of enemy players and just stay attentive. Oh and if a guy is camping in one spot and you get killed by him at least 2-3 times from that same spot, don't keep trying to kill him. Just avoid that area. The guy will usually get killed sooner or later or realise no one is coming his way so he'll move.
Stay Scoped - When sniping after geting a kill do not release the scope for 5 or more seconds so if they watch the kill cam it makes it harder for them to figure out where you are sniping from.
Boom.. no headshot? - Never aim for the head with a pistol, aim for the neck, they are not 1 hit kills, by the time the second bullet flys out the recoil will have aimed for you.