I'm founder of Sellfy and we have many ebook publishers on our platform - we see what works and what doesn't so I'm happy to share few tips if you are interested.
Here are few quick tips:
1) Build your audience beforehand (email, social) as it will power your sales once you launch your book.
2) Try to do guest blogs and get reviews from other bloggers on your book. Send them free copies etc.
3) Launching is easy but holding the revenue steady requires a lot of work so plan to spend some time post-launch to promote your book.
*) To optimize revenue think about several pricing options.
Feel free to contact me maris[at]sellfy for more info!