What's your opinion about the single best (most effective or highest success rate) way to make money online?

I suppose you ultimately make more from selling something than from screening ads, I have not made more than $100/month from ads, and that's on sites with 30k visitors per month.

If you've got a lot of unique and well-written content, and submit your site to directories and search engines, should it result in success? Or are there other factors involved? What's your experience and best strategy? -- or best strategy that you'd be willing to share ; )