Play classic 6v6, it's a lot easier to get kills, be patient you'll get there! (: Oh and also make sure to try your best to get killstreaks those killstreaks will boost your % up fast. Listen to some good music, trust me everything goes faster when you got a good song to listen too. You don't have to get kills with the last word, you just have to have it equipped. Try hipfiring, lots of people have told me that hipfiring makes the Last word easier to get kills with. Good luck! (: