As a player who has put in over 70 hours into search and destroy, I hope i can help someone become a bit better!
The class I mainly use:
2 EMP or Concussion's
I use this class as a hybrid of rushing when on offense and playing defensively on defense.
Now to explain why I use what I use.
Suppressor because it allows me to not show up on the enemy map, and therefore stay alive easier and longer.
Flak Jacket to not get killed by that c4 or claymore.
Ghost to stay off UAV when on offense.
Fast Hands to get those stuns out fast on offense. If played well you will not need toughness. Don't be afraid to dropshot.
Dexterity to ADS faster after sprinting.
Stuns to make sure i get that kill with minimal damage.
C4 if you run out of ammo or the enemy runs away around the corner.
Combat knife can be used to pick up a extra gun.
Now for a few tips and tricks:
Don't be afraid to dropshot or crouch.
If you know the enemy will be rushing, don't be afraid to wait them out.
If a enemy sees you trying to enter the building they are in, pretend to go around to the other entrance and double back.
If you are the last alive on offense and have planted the bomb, try to keep the enemy distracted and scared, so if they do kill you, the bomb explodes before they can do anything. Example throw c4 at bomb site to scare them, maybe shoot a few bullets at them, etc.
Hipfiring in CQC is quite effective with this class.
Now the tips for fighting those players some of us hate.
Sniper/Quickscoper: Avoid medium to long range engagements. Try to go around another way and get close. You can always dropshot or crouch so their quickscopes miss.
Shotgunner: All I can say is dropshot them so their first shot misses, have them dead before the second hits.
Assault Shield: Try to go around the side, STAY CLOSE so if they use their C4 it kills them as well.
LMG's: Try to get in close, their ADS time is slow and their hipfire is not accurate.
Target Finder: Use cold blooded, but most TF kills can be easily gotten with a reflex sight.
Knifers: Hipfire while moving backwards in a zigzag fashion.
And one last tip, don't waste the point on a reflex sight if you can use the iron sights. Try it!
Thanks for reading, and feel free to post your own tips or add me on Xbox Live. GT: TheMasterSSA