One thing I personally feel should be mandatory, which isnt, are universal callouts. More often than not, I would hear a callout of "behind you" so I turn around and start looking for an enemy player (as im sure most would) and then get shot in the back. If you see a teammate in front of you just before you get shot, take a mental note of who that teammate is and if you even begin to get shot (screen turning red) It would be a good idea to say for example "Fr0zen, Behind you" That is one example, another is where 1 player might have a callout for a certain location of the map and another player has a different callout. This tends to get very confusing for some players as they wont know what you are calling out. Sometimes I try to call out a general area that most players would know "B flag" or "2nd floor body shop" It keeps it fairly short while giving a decent callout to prevent that enemy from getting another kill. "Hey theres a guy at um...at the body shop" By the time you said all that, that enemy probly picked up another 2 kills. Keep your callouts as short as you can while still giving detail on where the enemies are. Callouts when you spot an enemy are good as well. Sometimes you might not have a good shot to take so to call out an enemy you just saw would be very beneficial to achieving a win. Keep em short but to the point. Also, listen to the AI in the game as you play. They sometimes give GREAT callouts. "porter building, left side, 2nd floor" You will also hear a close by teammate's AI say "roger, im on it" That means that player is looking in that general direction. Take note of which player that is and let them know there is someone in the porter building with the same callout the AI used. With using effective callouts, games end quicker to get more games in.
There was a game if I remember right, OpTiC played of TDM and the game was over in under 3 minutes because of the constant callouts. Now im not saying for us to become a hardcore competitive clan like OpTiC but more to have effective use of our time playing games. Dont get me wrong, im NOT saying to not have fun and joke around because lets face it, its a game and it is for our entertainment and to have fun. There is always time for fun while playing the game effectively.