First figure out for sure just what you are you looking for out of a startup. Personally, my reason for wanting to work for a startup compared to a large corporation is to get to have more influence and work on a wider variety of interesting problems across different domains. And you can get that without needing to be in a business that has potential to grow to a billions of dollars valuation. But if you're interested in maximizing your chances for crazy sums of money while you're at a time in your life that lets you take risks (and there's nothing wrong with going after that, just don't make plans around an assumption that it'll happen), that'll drive your search in a different direction.
