Perk 1: Ghost, Hardline, or Scavenger (only if you're amazing use Scavenger)
Perk 2: Scout or Sleight of Hand
Perk 3: Last Stand (sometimes when you have Last Stand those last few shots actually shoot out of your gun)
Lethal: Semtex
Special: Anything will work. I don't recommend decoy and highly recommend smoke, flash, or concussion (none of those 3 are better or worse than each other)