I have sold tens of thousands of my language course over the last few years, but don't really know how to make use of these buyers. The feedback is very positive but the nature of language learning means most don't need to continue to learn once they've reached a certain level, so there's not much to be made from continually bringing out new courses. If they all live in the same area, live courses would keep them motivated to continue and would be profitable, but they are scattered worldwide. I thought of skype 'clinics' for extra lessons, but what you can charge an individual does not amount to much for the time involved.
Any ideas on how to build on the customer base?