The person that doesn't judge you when he knows you did something weird or stupid and just tells you important things.

When mentoring beginners: keep it simple.

ik that you know way more than they do, and you want to share all this information, but it's generally too much to digest. Focus on the biggest points and explain it to them clearly. Don't spend an hour explaining every variation of what they should have done.

Teach them how to understand the game not become a carbon copy of yourself

give a man a demo review and he stops feeding for a day... teach a man to demo review and he stops feeding for a lifetime...

but honestly teaching someone heuristics of how they can continue to grow themselves is the most helpful way you can mentor someone. for example, breaking demo reviews down into specific situations (uber ad/disad, player ad/disad, mids, etc) and understanding them both generally and on each map can help dilute the chaos of learning. understanding general principles is way more important than analyzing specifics. also, mindsets such as making sure to focus solely on your own game rather than thinking about your teammates' mistakes go a long way.

KevinIsPwn has the best guide I have seen for how to teach TF2 https://youtu.be/AOTOAZA18kw

I try to teach basic concepts, explain how I come to the conclusions I come to, in an attempt to help students be able to think critically about their own play.