Earlier post, I was telling that you can use Acrobat 9.0 encryption features to enhance your eBook ventures. But that is not the best practice.
The best practice is by the way of Adobe Digital Edition.
Adobe Digital Edition is a software for you to view the eBook (similar to PDF Reader).
So, publishers can use InDesign to publish eBooks into PDF/A and EPUB formats supported by Digital Editions.
Also, make use of Adobe Digital Experience Protection Technology (ADEPT) to protect illegal activities.
How it work is straight forward.
Use InDesign to create eBooks and save into PDF/A format. Subscribe to ADEPT (hosted service) and upload the eBooks there. Copy the link from the ADEPT server and publish it to a web site (i.e blog), then let buyers download from there. Buyers will download a ETD file (Acrobat eBook Reader EBX Transfer Data File) which contain information to the eBook and also have to download Adobe Digital Edition (software). Use the latter to open the ETD file.
Only Adobe Digital Edition can read ETD file and the former can has features to make sure that illegal activities are not done towards that eBook, for instance, it will make sure that you have to activate the incumbent computer in order to read the eBook. If you chose not to activate incumbent computer, then the eBook can only be read on one computer; the incumbent computer as well.