I probably found it by way of OB, and I'm not sure how I ended up there.
One thing that would probably help is for Eliezer's book on rationality to get published, but I don't have any idea what a reasonable schedule for that is.
Other than that, I recommend that LWistas recommend any articles they especially like on their blogs and on social media.
I was reflecting the other day about how I learned about LessWrong. As best as I can recall/retrace, I learned about LessWrong from gwern, who I met in the #wikipedia IRC channel via an essentially chance meeting. I'm wondering how typical my experience is. How did you come to LessWrong?
EDIT: Optional follow-up question: Do you think that we (the community) are doing enough to bring in new users to LessWrong? If not, what do you think could be done to increase awareness of LessWrong amongst potential rationalists?