Sprint planning is a key event in the Scrum framework that sets the tone for the upcoming sprint. As a Scrum Master, it is important to facilitate the planning session  in the best way possible to ensure that the team has a clear understanding of what needs to be accomplished and is motivated to achieve their sprint goals.

Here are some tips for facilitating a successful sprint planning:

1. Start with Clear Goals and Priorities: Before beginning the planning session, make sure that the team has a clear understanding of the sprint goals and priorities, whether this be around particular user stories or a particular project. This will help them focus on what is most important and ensure that they are aligned with the product owner's vision. Also, ensuring that Product has prioritized the backlog beforehand will help immensely throughout this ceremony, so follow up and make sure this is done beforehand.
   
   

2. Involve the Entire Team: Sprint planning is a team effort, and it's important to involve everyone in the process. Encourage active participation and make sure that each team member has a clear understanding of their responsibilities.
   
   

3. Come Prepared: As the Scrum Master, you want to come to the meeting prepared with a few metrics: how many story points the team is on track to complete this sprint, how many user stories the team is completing on average, and the team capacity for the next sprint. Having this information and sharing it with the team before you get into moving user stories from the product backlog to the sprint backlog will help set the right expectations around how much work the team should be taking on.
   
   

4. Break Down the Stories: User stories are the backbone of the sprint, and it's important to break them down into manageable tasks. If you're coming across larger stories, then work with the team to identify the tasks required to complete each user story, estimate the time required, and assign tasks to specific team members. That being said, if all of this has been done successfully in refinement sessions, then this shouldn't be something you have to worry about.
   
   

5. Review and Adjust: Once the team has selected and prioritized the user stories, it's important to review the plan and adjust. Identify any potential issues/roadblocks/dependencies with the team and adjust the plan as needed. As an added cushion, you still have a day or two to make changes before the sprint begins if your sprint planning isn't happening on the final day of the sprint.

In conclusion, facilitating a successful sprint planning requires starting with clear goals and priorities, involving the entire team, using timeboxing techniques, breaking down user stories, prioritizing tasks, and reviewing and adjusting the plan. As a Scrum Master, it is your responsibility to ensure that the team has a clear understanding of what needs to be accomplished and is motivated to achieve their goals.