I would add "Make sure every stakeholder has the same idea what the project will be". I have seen a lot of projects where once you talk to all stakeholders it becomes pretty clear that there is no shared understanding of what we are trying to achieve. Especially be wary of senior managers injecting their pet ideas.
See also: https://www.youtube.com/watch?v=8fz-AowdiL8 - a 1 hr webinar from the folks behind Microsoft Press' recent Software Requirements books (Seilevel) on how to document these requirements and make sure folks are on the same page.
This 1000 times. I can't tell you how often I've seen this happen. Many times it's at least a factor in failed projects.
Clues this might be happening: senior managers pulling you aside to discuss their ideas for the project. Getting different questions on project updates than the goals you're building towards in scrum. Constantly changing short term goals.
