1. Make the registration process as simple as possible for your given target audience. Far too many companies confuse registration as a place to gain marketing insight into their users. Marketing will hold back registrations at the onset, when marketing makes far more sense to be done later (with proper marketing incentives, such as give-aways).
2. I despise registrations in order to read information online. Those are almost always purely marketing-driven and have little to do with providing a better user experience for the individual. Newspapers are doing this more often instead of less often (and they wonder why they’re having such a difficult time groking the Internet and staying in business).
3. Test, test and re-test across multiple platforms and browser (with multiple privacy settings) any registration system you devise, and ensure it gives users all the privacy options they demand in today’s world. I’ve seen some widely used registration systems that still have basic usability snafus in how they handle cookies and logins, making a user login more than once.