If you're anything like me, just reading that word filled you with a sudden sense of intimidation, inferiority, awe ... and, whoa. Wait a minute. What's that other emotion huddled there in the corner, being beaten up by our fear of failure? Is that curiosity?
If you've ever used Ask Mr. Robot and asked yourself, "How do people determine which of our stats are better than others?" If you've ever played a healer and asked yourself, "How do people figure out which spells are the most efficient to use at which times?" If you've ever played a DPS class and asked yourself, "How do people figure out what my spell priority should be?" Basically, if you've ever wondered how some of our game's brightest players find the answers to our most pressing questions about game mechanics, then there's at least some small part of you that's interested in theorycrafting.
So, great, you're interested. Now what? How the heck does a person get started, especially when theorycrafting seems so complicated?