#1: See your team as equal players, no one is automatically a noob, nobody automatically a pro
#2: Convers with your team in team-say by pressing "u", do this often, remain calm and discuss
#3: The weakest link of your team is the newest player, don't call him a noob and don't abandon him
#4: Pinpoint the weakest link, support that player and give him tips instead of going ape♥♥♥♥ on him
#5: Try to keep your team focused, there are some whiners out there, get them under control
#6: Keep your team spirit up, tell people they do well or how to do better in a calm way
#7: Point out weaknesses of the enemy-team, discuss them and use them to your advantage
#8: It's perfectly fine to joke around, use it as a team-anti-depressant
#9: If a strategy didn't work, don't ♥♥♥♥♥, discuss and try something else
#10: [MOST IMPORTANT RULE] Don't be a ♥♥♥♥♥, don't hate on others while you do bad yourself
#11: If you are a leader, be a leader not a boss, show them what to do instead of just giving orders
#12: Don't run into your team-mates fire
#13: Don't shoot your team-mates if you don't have to (like in a CQB battle its inevitable)

That are rules built by common sense, one advice for MM lobbies I can certainly give: If there is a whiner that calls everybody a noob and you feel everybody hates him, kick him for your own sake and the group spirit. It's better to play with a dumb BOT instead of someone makeing you angry all the time by typing stupid things in both general and team chat. Allways try to be friendly, even if it drifts towards a loose, tell what could have been done better, how to improve and realize that YOU are not the best player in the world either. The other team could have been just better than you were or you played with more inexperienced players, sometimes however you get a group that rocks everything and you will feel like a CS Pro, trust me.

In conclusion, teamplay is not about trying the hardest but having the best team spirit in the game itself. All Are completely random if you don't play with friends. Designate roles in your group, Snipers, pushers, defenders and the bomb carrier as a VIP target. This may help you improve your random-group teamplay a huge chunk.