Best Practices for AS3 Preloader

kirupaI was wondering what is the method that is most efficient to create a preloader for a full-scale flash site. I mean something big that probably has multiple movies being loaded that a major company would develop.

Is the preloader created as its own SWF and calling separate SWF’s created from another file? Or does the preloader appear on frame 1 and the rest of the content on frame 2?

Just want to know whats best/recommended.

Thanks!