I felt like typing a little stuff lol, anyway a few more useful tips you guys might enjoy
TIP 1 Stun grenades are faster to throw than flashbangs, fancy why I use them more, flashbang might have a more lasting effect, but if an enemy is rushing in on you, a quick stun throw will have them easy to kill, also I had a lot of direct hits with it xD
TIP 2 If you happen to shoot down and enemy and he goes into last stand (REALLY ANNOYING), And guess what, your bullets are out or nearly out, just throw a stun on him, even if its not a direct hit, the blast will kill him, and you can even pull out your microphone and yell PWNED!
TIP 3 If you like quickscoping with the intervention, the best way to do it is NOT just rushing into the enemy and start pulling out shots till you hit it... Unless you are Ireapzz, then its fine lol, anyway the best tactic is to run from cover to cover and always watch the areas where you know the players come from, also keep in mind the current spawn area of the enemy team, so you dont get rushed from behind, use UAV as one of the killstreaks, it WILL come in handy, after you have that great spot, just wait for them to show up, line up the crosshairs with the enemy, and take the shot! IMPORTANT! Do NOT move when you do this, as itll end up in epic failure, believe me.
TIP 4 Play to have fun, you will see how much it will reflect on your score, if you start to get angry it will just make you wanna rush in for kills and eventually you will get pwned, even if you happen to lose and not have that much of a good score, you were playing for fun, so you wont be angry either. Avoid arguing over chat and/or microphone, just ignore it and play!
TIP 5 Never stand still unless you are camping, always move around and watch every corner, the more you move around, the more your senses will be ready for a surprise and the better will be your reaction, specially when quickscoping.
TIP 6 (last one) Play wise, say you are a knifer, and you are running and suddenly an enemy shows up, but he is too far away to be knifed! OH SNAP, what do you do? Stand still? You will die, Run really fast and try to knife him? You might get lucky but doesnt really work everytime... Say theres an entrance to a building and/or a vehicle such as tank to your right/left, simulate running inside/behind the car, and then suddenly come back out, if the other guy is not playing wise, you will see he will try to intercept you the way you supposedly went, and since you just simulated you will PWN him on his back, this also works with any other type of classes, also use your ears, dont just walk and run all the time, (unless u are using ninja), try to go around crouched more often, specially in objective games, such as Search and Destroy, your enemies wont hear you, and you will not hear ur own footsteps, making it easier for you to hear other environment sounds, such as bomb planting, enemies moving, enemies cooking nades, enemies shooting, even reloading! And the last but not least, keep an eye out on the radar every once in a while, but not for too long! also dont randomly shoot unless you have a reason to, it will just wasted bullets and reveal your location on the map, unless you want to trick an enemy by giving out your position then hiding and waiting for him to show up.
Hope you guys find these tips useful, now im off to play! peace!