Mayby the problem is that you are alone. With one or more friends you won't be killed as quickly as you do now. Probably your friend will be shot down, but than you have the chance to kill that guy. Also, do not rush. Mayby it seems cool and you get a lot of kills, but only the professional players will succes. And if the whole team is on the other side of the map and you are the last man, the spawns are gonna be on the other side of the map, so that's why you got knifed from behind. So Watch your back and stay with your friends.