Can I sit for repeat clients only?
You certainly can! If you feel that the current client you have at the moment is keeping you a very busy, then you can just change the Customers Accepted setting on your Calendar page. This is found in your profile under 'Calendar' tab.
Watch the following video for a brief summary of how to update your calendar: https://www.youtube.com/watch?v=YOQDGtI6K8w