To be completely honest, its the title that gets me first. When I look in the hot topics section, or the zero replies section, I look for something that interests me. If I don't see a topic that catches my eye, then I start to dig through the sections that interest me most starting with religion.
Of recent I have found that the Related Links have a tremendous pull on readers. I guess because of its' position / location when scrolling down you just cannot help but notice. The trouble is that it take a lot of work to fill them in and so I cannot get it within enough threads, because there are so many here!
Usually what sparks my interest about a thread is the board its on and the title. Titles play a large part on making a post interesting or not. I have to be in a certain mood to post in certain boards, so that plays a large part as well. A lot of times I go to the Unanswered posts a lot and try to reply to those.
If the title is very provocative or simple, this captures my interest and compels me, to read the message immediately. Of course, the topic is another factor that influences me to read because I would not select a subject that I have no interest in. I believe that the way the person presents the topic is extremely important since it projects an aura, that may entice or repel me. Believe it or not, the board and who started the thread does not encourage me, to read the message.