TIP 1. DO YOUR HOMEWORK
The worst thing one can do is come unprepared. First of all, know your strategic goals. Are you searching for investment? A career shift? Network expansion? Act accordingly. Check every possible guest list, shoutouts on Twitter or whatever you'll find and decide what kind of people you need out there. And do your best in trying to reach out to those people before the event (E-mail, Twitter, Facebook, LinkedIn, whatever works for you) and try to arrange the meeting on the spot. The more advance work you do the more results you get.