Take advantage of aim assist
Most "hardcore" players in the first-person shooter space despise things like aim assist. But, for players that are newer and want to have more fun, this is a great tool. All it essentially does is move your aim cursor towards the nearest enemy.
You'll see it in a game like the aforementioned Call of Duty too but it can still be tricky to get that perfect shot sometimes. In Critical Ops, it locks on to your target a little better. It doesn't mean that it's an instant kill by any means so there's still a bit of work you need to do.
However, if you're struggling with your aim, and getting the gun pointed at the enemies, then the aim assist is helpful. It's not a pure lock on like in a game like Grand Theft Auto V, but it'll sort of sway its way to where you want it. This way, it's still up to you to make the final blow despite the help.
Throw those grenades
As with many shooters, players will tend to find some safe spots where they can do their damage. If you have a grenade or any projectile on you, feel free to toss over a wall where you think the enemies are. It's a good strategy to sort of know for sure if enemy players are there.
And of course, if they hit, then you may rack up a kill or two in a one-shot. Heck, I would even say to throw a hail mary into enemy territory. As silly as that may sound, it's a good way to keep them on alert and may expose them.
And once again, if the grenades do hit, then watch the boom, and get the kills. But even if you don't hit, you know you'll likely see some movement. From there, take them out. I understand that you can only use a grenade a limited amount of times, but it's worth the shot to give them the toss if the time is right.
Take a look at your loadout
Before even hopping into a match, go ahead and take a look at your loadout. Loadouts are always very important to success in great FPS' like Critical Ops. Take a gander in the main menu and see what you have at your disposal.
You'll see that many weapons are available to you from the jump. See which ones that you think could benefit you the most in battle. Take a test run in a match. You have multiple pistols, machine guns, and snipers to choose from among others.
You can also unlock some cool new skins for each weapon also. The designs are pretty sick, so unlock theses and head into battle with style. There are some slick melee weapons available too but you need to purchase these. Keep on playing, and you'll be enjoying the new skins, melee weapons, etc in no time.