I know this is maybe not the best thing for someone in marketing to say, but I think the relevance of advertising is quickly declining. Now, don’t get me wrong; there’s still a place for effective SEO, creative strategies and conversations with customers, however perhaps the best marketing for your product is (brace yourself) to start with a good product.
The thing is, Google and other search engines don’t release the details of their algorithms so we never really know for sure what criteria they use to judge a website’s rankings.