Wow can't believe no one has a proper answer to this question. One way to increase win/loss , KD ratio is to get a "farming buddy". Create a Blind Eagle room with password and invite your farming buddy. Once the game starts, do not kill each other. Take each other's KEY(you will get +2 score) , and drop it on the floor so your buddy can pick it up. This will result in 3 score , 1 for returning the key, and 2 for taking the key.
There is also a longer way to increase win/loss , KD ratio. Create a escort room (Scorpion is the best) and just keep repairing and destroying tank.
Hope this helps !