Ask HN: Advice for Scrum Master for First Spring Planning

What advice (from the trenches) would you give for a Scrum Master who will facilitate the first Sprint Planning for a team who is starting now this process. I'm imagining there is a lot of experience here with these kind of processes and I'm looking to find out practical insights. Edit: I know that there were a lot of articles about Scrum and about issues with it. Still some companie are using it or actually start using it because it might seem there is no alternative (in their point of view).