Here’s some home-spun wisdom that should serve you well regardless of your game mode!
Time to Team Up: After spawning, one of the best options you have is to find another teammate near your location and stick with him as you both move throughout a level. Staying near a teammate has a number of benefits beyond just doubling your firepower. You’ll also split the chances that any given enemy you stumble across will fire at one of you, and if you let your partner take the lead you’ll have a better chance of learning where enemies are from around a corner by paying attention to when and where he’s firing (or where the bullets are coming from when he goes down).
Likewise, you can cover your partner’s back if he decides to peek out a window for a bit, and he can help avenge you if he spots your skull marker indicating that you’ve been put down. You don’t need to stick with the same player throughout a round (and the game’s spawn system makes this difficult, regardless); just find someone close to you when you pop into the map and start following them. They can’t say no, after all.
Sticking close to a friendly player will protect both of you and double your firepower.
The drawbacks to forming these impromptu fireteams is that you’re more likely to both be killed by a Betty or a grenade or an enemy with an especially rad scorestreak reward. But, over time, you should wind up with more kills than deaths if you stick close to a teammate.
Know Your Ranges: A bullet’s a bullet, but many bullets aren’t going to deal the same amount of damage at all ranges. You can check these distances in your weapon select screen, where each weapon has a Range factor to consider. Stick within this range, and each bullet you fire will deal maximum damage; using a short-range weapon to fire on a distant foe will require more bullets before they go down.
There are two exceptions to this: sniper rifles do flat damage to any target that you can see; there’s no maximum range for these weapons, so feel free to fire at anyone who wanders in your field of view, knowing that they’re going to fall down just as easily at max range as if they were standing next to you. By contrast, shotguns deal no damage at all to targets beyond their max range, so don’t bother firing at distant targets. You won’t hurt them, so you’ll just be showing your location to your enemies.
Take Advantage Of Penetration: Yes, we know there are plenty of jokes to be made about the term “penetration,” but you’re not going to find it very funny the first time you check a killcam and see someone shooting you through a wall. All weapons have the capability of penetrating thin cover to deal a reduced amount of damage to enemies hiding behind that cover. “Thin cover” here refers to, well, thin pieces of material that often border windows and doors. You won’t be able to penetrate large, thin objects like stone buildings or cars, but many bullets will be able to pop right through thinner materials like plywood walls or cargo containers.
Taking advantage of this is key to getting some absolutely filthy kills, and you’ll need to be aware of psychology to do so. Many players who fire out of windows and other spots that are bordered with thin cover will retreat when they feel return fire coming their way; the most common response is either to run away entirely or to duck behind the cover and start reloading their weapon. If you’re tracking an enemy in a distant window and have a full-auto weapon, it’ll often be profitable to simply keep firing through the thin cover that they’re hiding behind when they retreat. You can check your crosshair to see if you’re hitting anything; if not, simply follow their lead, duck behind your own cover, and reload. If you are, keep firing until your clip is empty, and you’ll sometimes be rewarded with a kill. (High-end attachments like MMS can boost your chances of kills in situations like this.)
You can fire right through most light cover. Handy if you have an idea of where your opponent is.
Penetration kills are more likely to happen with high-powered weapons like sniper rifles, light machine guns, and shotguns (at close range), especially if you add the FMJ attachment to your weapon. Assault rifles and SMGs can get some penetration kills, but their damage will drop off pretty significantly if your target isn’t out in the open. Pistols can’t be expected to get many penetration kills at all, but you may occasionally get lucky.
Knowing the map will help you gauge whether or not you’ll want to bring in a penetration class build. Maps like Cargo, which feature a lot of thin walls and encourage people to hide inside them, are often the best bet for penetration builds, but if you pick your map correctly, you’re going to get some absolutely cheap kills. And any kill that has people claiming that you’re a wallhacker is a satisfying one.
Rebind Your Mouse Buttons: If you’re playing on the PC, be sure to check your mouse bindings in the settings, especially if you have a five-button mouse. Your side mouse buttons seem to be unbound by default, so you can feel free to put anything on there that you like. One obvious choice is to set your knife swing to one of those side buttons, making it much easier to access in the heat of an up-close-and-personal firefight. Tactical or lethal equipment is another good choice. You can even rebind your middle mouse button, but you should probably only bind this to something that won’t get you killed if you accidentally wind up scrolling your wheel and switching weapons. Scorestreak activation might be a good choice here, since you often trigger that without enemies around.
Reloading Is A Dangerous Thing: Reloading your primary weapon is often going to be one of the most dangerous acts you can perform in Call of Duty, mostly because it’ll leave you largely defenseless against any enemy that happens to spot you while you’re incapable of firing back at them. Different weapon types have different reloading times (with LMGs being the slowest of any weapon to reload), but the important thing to remember here is that almost any weapon will take a longer time when reloading a completely empty magazine than it will a partially depleted one. It’s a small difference, but Call of Duty has always been a game of split-second margins, and as such it’s usually worth attempting to reload your weapon when you have a round or two left in it, if possible.
This is precisely the last thing you want to see if you’re reloading.
You’ll rarely be weaker than when you’re reloading, especially if an opponent startles you while you’re in the act. Attempting to reload while you have an enemy in the room is usually a death sentence, so if you’re in the middle of a reload animation and someone gets close, it’s worth cancelling the animation by switching to a secondary weapon, sprinting away, or attempting to close in on them for a knife swing. You’ll always want to be in cover when reloading, but if you spot yourself taking damage while you do so, your best bet is often to mash your sprint key and relocate.
The Fast Mag or Extended Clip attachments will reduce the amount of time that you spend reloading, but if you’re using an LMG or Sniper Rifle, there’s little way to avoid a somewhat extended reload time compared to an SMG or Assault Rifle. Try not to reload unless you’re around friends when using these weapons, as you’ll be very vulnerable until you’re done doing so.
Know When To Hipfire: You will occasionally sprint through a room and find yourself face-to-face with an enemy too far away for a knife kill but whom already has you in his sights. Your choice here is between attempting to raise your weapon to fire down the sights (which is painfully slow for the sniper rifle and LMG), or simply fire from the hip and hope you make enough contact to take your enemy down.
This choice is going to rely on a fair amount of experience, including knowing the basic ranges that your weapon is lethal at. Any weapon can get a kill when firing from the hip at point-blank range, but that accuracy drops off significantly as the distance between you and your target increases. SMGs and shotguns will fare best when fired from the hip, but LMGs and sniper rifles will tend to act a bit like blaster rifles from Star Wars when fired at anyone outside of your immediate vicinity from the hip, i.e. you’re going to miss, rather a lot. These are also, uncoincidentally, the weapons that take the longest amount of time to shift into aim-down-the-sights mode. If you’re startled by an enemy while using one, your best bet is often to either back away and cover your tracks with a grenade, or charge forward for an attempt at a knife kill.