I've acted as a dev lead for a few teams and recently been a tech lead for a fantastic project with some awesome people. This is a reflection of few traits I've picked up over the course of my experience.
Be an advocate for change
Always, try to make it a better work place and push for an ego free culture for your team so that everyone can freely share opinions. Acknowledge your team members opinions even though your views are vaguely different.
I believe this is a key trait for everyone in the team, not just tech lead. Challenge opinions/decisions/proposals politely. By doing this you will be likeable human being!
Write down everything
Yes, write down everything! like I am doing here. everything!
Take the pain
A tech lead should go through everything that everyone in your team is facing. Be it a tech hurdle/complex logic/architecting/writing unit test cases. Do it. You have to go through it and make it better.
more to come...