Devote time
Although this is a personal decision and greatly depends on how you plan to be involved in your course, we believe a couple of hours a week is enough time to stay up to date with your students' progress.
Prioritize tasks
Similarly, when you're short on time, prioritize answering core questions that enable the student to advance in their learning experience and provide feedback on your students' final projects, even if it's brief.
Pay attention to the little things
Be nice, try to personalize your messages to students, and be sure to 'heart' (like) the comments you get.
Be precise
Try to avoid generic responses and put thought into your answers while providing constructive feedback that helps the student improve their skills.
Follow topics
Remember, to get notifications about all the activity in your forum, you have to follow each posted topic.
Interact
Keep your course buzzing with activity by posting new topics with links or projects your students might find interesting. You can also share news about what you've been working on and things you enjoy, such a book you're editing, an exhibit you've seen, a project you're excited about, inspiring references, etc. There are plenty of ways to connect with your students, find what works best for you.