Something that I've found to be very important in determining whether a submission is successful (here on HN and on reddit) is the first comment. If something

Something that I've found to be very important in determining whether a submission is successful (here on HN and on reddit) is the first comment. If something has a handful of upvotes, people will often check the comments to see if the link is worth their time or not. If the first comment is "Wow, this is amazing! Why is this not on the front page?" you have a much better chance of making it than if the first comment is "This is blogspam. Move along." Once a post gets critical mass, and there is a conversation going on, people assume that the post is worth reading, and invest more time, which creates more upvotes. Of course, this isn't the best filtering mechanism since it is effectively the wisdom of the crowds.