What have been your experiences with interns? Specifically marketing interns.

Focus on single very specific tasks to start with clear deadlines. Explain the why of the tasks. Consistent engagement on social with people is as valuable as posting. They'll call in sick a lot.

Have a structure in place for their internship, complete with tasks and deadlines, hours placed aside for learning/teaching/reading etc, and have regular catchups to make sure they're keeping pace and taking in the information.

My experience has shown that an intern either quickly becomes a full-fledged member of the team or we say goodbye to them forever.