Get yourself a void shotgun and machine gun, they don't have to be high quality. Then play control and do some camping. Camp the heavy ammo spawn and be greedy, take the ammo unless someone else from your team is close by. Use your void grenades unless you're a hunter. Stay close to teammates and shoot at everything. Don't get too frustrated, you'll have good matches and terrible ones. If you stay at or above 0.6 k/d you'll get it done soon enough