I would suggest Dom or Hardpoint would be the easiest.
Especially when enemies or on a flag or what not, maybe flashbang or stun the beejebus outta them prior.
They will come naturally, use portable radar and UAVS you need the intel before you swoop.
There is a healthy delay of maybe 3-4 seconds between the 1st and second kill allowed, as long as it's in the killfeed.
You could try FFA maybe? Or Groundwar as there are maybe more opportunities available.
Flanking is key as well, try go round the outskirts of the map and work your way onto their side.
Alternatively you could post up on a high traffic area or hotspot and mount up for accuracy.
B flag Dom on a roof or window with height advantage, lay prone facing a hardpoint so your difficult to shoot.
Or run about like a madman and rush the shit out of them and be really aggressive. Pick your poison my friend. Who cares how you get it done.