How to make the best of meetings?

After reading this thread [1] I saw some good advices like: do a meeting on a room without chairs, cost in people hours, meeting with less than 4 people, make an agenda.

Do you have any other good hack for meetings?

[1] https://np.reddit.com/r/Nest/comments/4dbbgh/is_anyone_concerned_about_the_future_of_nest/