[Spoiler warning: I'm not going to give away specifics about the Lost plots from earlier seasons, but I will go into the themes a little bit, which may take away some of the surprise factor if you start from the very beginning.]
With the new season of "Lost" just starting, you may be a bit confused depending on where exactly you are in time (just like the characters). Maybe you've been away for long enough that you're having trouble remembering all the plot threads. Maybe you've caught up on your own timeline with the season DVDs. Or maybe, like me, you watched from the beginning in blocks of 3-4 hours per week, when the Sci-Fi and G4TV channels recently ran all the episodes to lead up to the latest season premiere.
I think this last way, in big multi-episode sessions, is the most effective. I remember hearing about some of the plot mysteries during the first season. Mysterious hatches! Polar bears! Seemed like the questions around those things dragged on for weeks and months. Viewing the episodes back-to-back gave the same feelings of wonder and suspense, but resolved the mysteries reasonably quickly.
Now is a significant time for Lost to resume, not least because we recently lost both Ricardo Montalban and Patrick McGoohan. Some say that Lost is like Fantasy Island. (Whatever you can imagine, can happen. Your fate may depend on whether you choose good or evil.) Others say it's like The Prisoner. (You'll never get away. Everything goes topsy-turvy. You can never tell whose side anyone is on.) The emphasis shifts each season. Sometimes things seem like magic, other times there are malevolent plots afoot.
I say the right way to think of Lost, is as a real-world, present-day version of Zork. (By the way, you can now download all of Zork I, II, and III.) You start with this giant unexplored area, that you map a little at a time. You find puzzles, locked doors and such, that take a long time to get past. The Dharma Initiative is like the Great Underground Empire, a Macguffin that is a convenient excuse whenever the creator wants a certain object or map location to exist. Once you know how to get past the obstacles and get from place to place, later puzzles involve going back and forth on long journeys through well-trodden territory. Landmarks that once were mysterious and intimidating, are now mundane and familiar. And when you try to solve the final riddles, you realize that actions and choices from the past have to go together in specific ways so that everything lines up perfectly in the present.
Here are the riddles I'm still waiting to find the answers to... I'll be peeved if these things don't get resolved by the end of the series! [OK, these might be a little spoiler-worthy if you haven't seen the first season or two.]
1) What is the origin of Hurley's nickname?
2) Who is the "him" who is supposed to be the replacement for the guardian of the hatch? Will anyone ever answer the riddle correctly?
3) How did Inman get to the island?
4) Why does it seem like the Dharma Initiative is still active in the background (think Inman, and the plane drops), when by all rights it should be defunct?