Best way to create user authentication

[eluser]Gukkie[/eluser]
Hi, i just wanan know wat's the best way to create a session/cookie authentication.

Shud i create a library or a helper to access the database to create a session if a cookie is detected or to redirect the user to the members area if a session is detected?

Currently im using a model and im calling it on every controller and i think its not feasable doing it this way.

Cheers!