Please Learn to Shut Up during a game.

B*tching about every single mistakes that your teammates make, helps not one bit. Our team was ahead a whole 20 kills at one point, but because one of our teammates make ONE Mistake, they just continue harassing and harassing them over and over and over. And eventually lost us the game because the guy couldn't stfu and focus on the game. We lost because it was 4v5 and he essentially just ran into the enemy team 24/7 without noticing because on typing.

So please, for the sake of your teammates and everyone else.

Learn to Shut the Fuck Up.