Suggestions from past supervisors

(though rose-colored glasses)

Meet with team regularly - at least once a week. If any team member misses two meetings, inform the instructors immediately (with cc to team member).
Force teams to circulate work amongst each other.
Teams feel they must hide their problems to get a better grade. Help them understand that this will make for more problems remaining in the final system and hence yield a worse grade.
Shuffle roles - spread them around. That gives team more experience and greatly reduces risk of problems being hidden or overlooked.
Discuss QA plan with team. Ask each team member to interpret.
"Don't trust teams. Given an opportunity they'll do something bad."

When a team member does not perform adequately, inform them (gently) at the first occurrence of this behavior. Postponing this (unpleasant) feedback does not make it any easier but will lead to problems down the road. Make sure to copy the "management".

Do a "dry-run" of the assessment that you will do at the end of the term and give that information to the individual team members. This allows you to distinguish between team members who are effective but quite and those who are just slacking-off.
Say whether each individual has appeared to perform above or below average on all visible components.
Give complements as well as criticisms, but sparingly since this may lead to complacency.
team member: "You've misunderstood me."
super: "Show me I'm wrong."