How many ways do you actively market your site? Do you rely on just one form like ppc, or do you do all sorts of stuff?
Obviously it's smartest to tackle all forms. Doing SEO you can do other things simultaneously, PPC is good if you have the initial capital to invest because you almost always lose a good deal of $ initially when trying to tweak your adcopy, your landing page, etc...
For each site I own, I: * have a blog * send out press releases * write articles I occasionally use PPC too to lift a site's visibility. I also have an email list, but I'm finding that the list is much less effective than blogging. Hope this helps. Cheers Angela