Conflict

In all reviews, of all media types from tv to books to movies, conflict or a tense situation often holds the most attention.

If the opening scene or sequence is of one of them threatening another with something (can be anything from the comedic to the dangerous). Then break down the why is bits of flash back for the other characters. Offer the viewer the different perspectives. This would act as both an introduction to the character's personalities and ideals, as well as give a starting point for the series.

What happens at the end? Leave it a cliff hanger. Lost did an excellent job of that. ;) I'd take notes from that show.