Leads--they're the one chance a writer has to draw the audience in. A title is often too short to really explain the article so its all up to the lead sentences. There isn't one main rule-of-thumb about them. It depends on the type of article being created, whether its a feature, news or a review.
Feature articles generally work well with creative and catchy leads for the reason that they aren't typically very serious pieces. Use your imagination. They can be a quote, a character description or a step back in time. News leads, on the other hand, should spit out the most important information immediately. If the article is about an increase in unemployment, say that right away. Do not waste time by dancing around that topic. State the facts and the continue the story with the next most newsworthy information. Reviews and other A&E articles of that nature can start off with a lead similar to features- creative. Perhaps the writer could start off with something unique about the band, author, etc. the audience may not know.