There really is no best way. What you need to do is utilize as many different ways as you can to get the best results, while tracking what kind of results your getting and from where. Ultimately just find what works best for you.
The key to marketing is to make somethign remarkable that people will use and tell people about (and online they will link to it and email it to friends). (Read some Seth Godin books!) One example is Website Grader. We built it a few months ago, and for the first 2 months we did not get much traffic. But now in the last 2 months, we have grown to over 35,000 unique websites being graded, almost all organic traffic too. By building something free, that people like to use and find fun and valuable, people will find you and you won't spend much money.