Not really, just practice I imagine. I've managed to score a couple of kills by getting a few hits on someone then lobbing grenades in the area. Still need one more. As others have suggested, if you're desperate to get it, 50 v 50 is probably the go.
Thanks, i did squads last night and surprisingly had a nice easy clinger kill. Bloke was in a room next to me so just had to make sure the clinger went inside.
I got a grenade launcher kill also, but found out later that whilst it's still technically a "grenade" that kills them, it doesn't count