I just came across an article by Paul Graham (who, among many other endeavors is a partner in Y Combinator) entitled How to Start a Startup. I was going to pull a few quotes and write an informative summary, but as it turned out I copied and pasted most of the article. So just go read it for yourself. Here's the intro to get you warmed up:

You need three things to create a successful startup: to start with good people, to make something customers actually want, and to spend as little money as possible. Most startups that fail do it because they fail at one of these. A startup that does all three will probably succeed.

And that's kind of exciting, when you think about it, because all three are doable. Hard, but doable. And since a startup that succeeds ordinarily makes its founders rich, that implies getting rich is doable too. Hard, but doable.

If there is one message I'd like to get across about startups, that's it. There is no magically difficult step that requires brilliance to solve.