How to implement a system involving multiple methods of authentication?

I'm starting a new project that depends on social networking platforms very deeply, so I have decided to avoid the normal registration-login mechanism and allow the users to create accounts by using Oauth or similar methods provided by services like Facebook and Twitter. I'm clear on how to implement them but I'm not clear on how my database and the front-end should be.

I'm looking for a theoretical solution because I might use this mechanism in multiple projects using different te开发者_开发问答chnologies.