1. Make sure to have Steam Guard on.
2. Have your profile on public.
3. Try to interact as much as possible with the Steam Community.
4. Don't cheat.
5. Get commended by your teammates.
6. Don't kick anyone out of the game even if they deserve it let your teammates kick them.
7. Do not block your teammates(grief) and don't shoot your teammates in the game.
8. Do more OVERWATCH cases you can even setup a bot to do it for you for FAST level and Green Trust Factor.
9. Like guides like this.
10. Add more friends.
11. Comment on many different profiles, discussions and guides like this one.
12. Make sure to rate this guide and award it if you want to see more guides like this!