I played less than 10 Dota match in my lifetime. On my first game i learned 2 important lesson:

1. I have mental disabilities.
2. My mother is a whore.

I was like ok, screw this game.

Even people who preach about manners failed to act on it when their patience are tested, especially Malay team captains(no vroom vroom here, i'm malay). Not all, but most of them. They like to boss people around. Always 100% right even when they're 100% wrong. You read about these team advertisement here, citing manners as requirement. I bet 50% of the captains failed in this department when the time comes for them to act on what they preach. How i knew this when i do not play dota? I watch my brother hop from team to team and see how the team captain act.

Another team requirement they failed, the willingness to accept criticism. They should changed it to "Team boss is always right, screw your opinion!". Being the youngest(16/17) around that time among players in their 20's, means he has no say. He had to learn his place. Now when i think about it, the minimum 18 years for team recruitment is a joke. You can be in your mid 20's but still more immature and more emotional than teenagers.

/end of rant.

I almost forgot, let me add 1 thing, being positive and treating people well is the key to success. Think more, act less on emotions.

I still remember earlier last year, my brother got paired with iceiceice and his friends on pub games. One game he screwed up so bad and the team lost because of him, guess how his teammates treat my brother? They we're laughing (loling, rofling) and kept telling my brother its ok. See, thats why they're the best, attitude! They got class! The next game my brother got paired with the same team and he managed to do well and i saw on stream iceiceice said his shackle was good and he's an above average player. Lift the pressure off your teammates, empower them. Not ordering people to do this and that.