A sequence is a series of multiple posts on Less Wrong on the same topic, to coherently and fully explore a particular thesis.
Reading through sequences is the most systematic way to approach the Less Wrong archives.
Map and Territory contains some of the most important introductory posts and essays.
If you don't read the sequences on Mysterious Answers to Mysterious Questions and Reductionism, nothing else on Less Wrong will make much sense.
The most important method that Less Wrong can offer you is How To Actually Change Your Mind.
Long sequences that have been completed and organized into a guide.
How to see through the many disguises of answers or beliefs or statements, that don't answer or say or mean anything. The first (and probably most important) core sequence on Less Wrong.
A series on the use and abuse of words; why you often can't define a word any way you like; how human brains seem to process definitions. First introduces the Mind Projection Fallacy and the concept of how an algorithm feels from inside, which makes it a basic intro to key elements of the LW zeitgeist.
A mega-sequence scattered over almost all of Less Wrong on the ultra-high-level penultimate technique of rationality: actually updating on the evidence.
Organized into eight subsequences.
The second core sequence of Less Wrong. How to take reality apart into pieces... and live in that universe, where we have always lived, without feeling disappointed about the fact that complicated things are made of simpler things.
A non-mysterious introduction to quantum mechanics, intended to be accessible to anyone who can grok algebra and complex numbers. Cleaning up the old confusion about QM is used to introduce basic issues in rationality (such as the technical version of Occam's Razor), epistemology, reductionism, naturalism, and philosophy of science. Not dispensable reading, even though the exact reasons for the digression are hard to explain in advance of reading.
What words like "right" and "should" mean; how to integrate moral concepts into a naturalistic universe.
The dependencies on this sequence may not be fully organized, and the post list does not have summaries. Yudkowsky considers this one of his less successful attempts at explanation.
A concrete theory of transhuman values. How much fun is there in the universe; will we ever run out of fun; are we having fun yet; could we be having more fun. Part of the complexity of value thesis. Also forms part of the fully general answer to religious theodicy.
The final sequence of Eliezer Yudkowsky's two-year-long string of daily posts to Less Wrong, on improving the art of rationality and building communities of rationalists.
Smaller collections of posts. Usually parts of major sequences which depend on some-but-not-all of the points introduced.
A collection of introductory posts dealing with the fundamentals of rationality: the difference between the map and the territory, Bayes's Theorem and the nature of evidence, why anyone should care about truth, minds as reflective cognitive engines...
Some notes on the incredibly difficult feat of actually getting your brain to think about something (a key step in actually changing your mind). Whenever someone exhorts you to "think outside the box", they usually, for your convenience, point out exactly where "outside the box" is located. Isn't it funny how nonconformists all dress the same...
Subsequence of How to Actually Change Your Mind.
Some of the various ways that politics damages our sanity - including, of course, making it harder to change our minds on political issues.
Subsequence of How to Actually Change Your Mind.
Affective death spirals are positive feedback loop caused by the halo effect: Positive characteristics perceptually correlate, so the more nice things we say about X, the more additional nice things we're likely to believe about X.
Cultishness is an empirical attractor in human groups: roughly an affective death spiral; plus peer pressure and outcasting behavior; plus (often) defensiveness around something believed to be un-improvable.
Yet another subsequence of How to Actually Change Your Mind.
If dragons were common, and you could look at one in the zoo - but zebras were a rare legendary creature that had finally been decided to be mythical - then there's a certain sort of person who would ignore dragons, who would never bother to look at dragons, and chase after rumors of zebras. The grass is always greener on the other side of reality.
Which is rather setting ourselves up for eternal disappointment, eh? If we cannot take joy in the merely real, our lives shall be empty indeed.
Subsequence of Reductionism.
On the putative "possibility" of beings who are just like us in every sense, but not conscious - that is, lacking inner subjective experience.
Subsequence of Reductionism.
Learning the very basic math of evolutionary biology costs relatively little if you understand algebra, but gives you a surprisingly different perspective from what you'll find in strictly nonmathematical texts.
How to do things that are difficult or "impossible".
How Yudkowsky made epic errors of reasoning as a teenage "rationalist" and recovered from them starting at around age 23, the period that he refers to as his Bayesian Enlightenment.