For effective balanced team play using the ICO system:
Everyone goes team 10 at the start of the matches to ensure no confusion when teams are picked (Yes just like dodgeball...and yes the last player picked is dubbed the "fat kid").
The 2 team captains choose either team 1 or team 9 (not a rule per se, but ICO has been known to freak out with too many interactions, so its safest to keep server interactions to an absolute minimum...plus its also just good manners).
Then another non captain player sends(via a whisper in game, typed /w PLAYERNAMEHERE you can also just press tab and your cursor will cycle through the list of people in channel after you have typed /w ) a number 1-9 to another non-captain player.
The captains choose a number from 1-9 in any order, first captain to post in chat gets the number if there is a "fight over the number 5" for example. Yes fights over number 5 have occurred in the past...
The other captain picks their number.
The sender posts their number.
The reciever of the number posts theirs.
The winning captain chooses to pick first, or defer and pick second (picking second in 4v4-5v5 games nets you 2 strong players if you know who you are picking).
The pick order breakdown for 4v4 and 5v5 scenarios:
The numbers in order represent pick order, the number value represents how many players are picked. So, the first captain would pick 1 player, the second captain would pick 2. This is because there has traditionally been a "king of the mountain" in sins, so to maintain game balance the best player's skill is offset by having two strong players to oppose them. This actually works quite well for keeping teams even.
4v4 pick order:
1211111
5v5 pick order:
122221
Get everyone to check the green checkmark and go!
Don't forget to say gl, hf (Good luck, have fun).
This can be done rather quickly if everyone participating knows what is going on.
Dealing with AFK players:
1. you can kick them to "wake them up"
2. If you are a steam friend you can send them a message via steam (useful if they are tabbed out of the game).
3. you can make fun of them
4. you can give them the countdown of doom.
5. you can choose to reform the game entirely if the host is the person afk.
Happy hunting 
When you get in game, type /a to speak to your allies.
