Make sure that potential team members have the time to engage in project work. Always check-in with the supervisors of prospective team members to confirm this. Check out prospective team members. When possible, build in redundancy for team members whose other work commitments are especially high, whose level of engagement may be questionable, or who are absolutely essential to accomplishing the project. Pick motivated team members who are excited about the project.
Enthusiasm is contagious and can be an essential ingredient to project success.