If you're new to Less Wrong, a good place to start is with the Sequences. The Core Sequences are the ones that focus on the fundamentals of rationality.

The Sequence index lists sequence posts in logical order. There is also a dependency tree of all of Eliezer Yudkowsky's posts from November 2006 to December 2008, and a couple of "abridged" versions of the Sequences: 1, 2.

Here is a sampling of various sequence posts:



Here are some "standalone" posts that are worth reading:





If you're interested in starting a Less Wrong meetup, How to Run a Successful Less Wrong Meetup is a guide for meetup organizers (pdf here).