Susanna Freymark starts with a clever list to sell a million books:
Back to book sales – here’s what you need to do.
1. Win an award for your unpublished manuscript.
2. Create a bidding war between publishers.
3. Sell you book to 50+ countries.
4. Travel the world promoting your book.
5. Accept a film offer on your book.
6. Give up the day job.
7. Write a sequel.
...and then goes into a little more serious detail to describe how to sell 5,000 books:
I'm not entirely convinced that I could use this method to push 5,000 book sales, but it can't help to explore all avenues, so do read her advice here: http://www.susannafreymark.com/how-to-sell-5000-books/