The SEO* principles
Google recommends the following to get better rankings in their search engine:
Make pages primarily for users, not for search engines. Don't deceive your users or present different content to search engines than you display to users, a practice commonly referred to as "cloaking."
Make a site with a clear hierarchy and text links. Every page should be reachable from at least one static text link.
Create a useful, information-rich site, and write pages that clearly and accurately describe your content. Make sure that your title elements and ALT attributes are descriptive and accurate.
Use keywords to create descriptive, human-friendly URLs. Provide one version of a URL to reach a document, using 301 redirects or the rel="canonical" attribute to address duplicate content.
Answers please
Search engine answers questions, and every day they are getting better and better
But they are only machines taught to do what they are told. When you perform a search, the search engine accesses billions of pages and information. By using mathematical algorithms it decides about two things. Relevance and popularity. The combination of those two factors determines influence and according to influence the search engine ranks results.
We, the search marketers, use accumulated knowledge of almost 20 years and evolution of search engines to fit your content into top ranks.
How do we do that?
Well, the principles are easy, but require hard work. We analyze keywords that are found on pages ranked by Google and combine gathered knowledge and analysis with your content. Then we adjust content and create a new one for constantly improving the position.
Search engines have limits, though
Search engines are not super intelligent entities that consume humans. They are organized, sophisticated algorithms taught by men. This leaves enough space for SEO expert to adjust online communication to be search engines friendly.
But, first of all, you've got to be seen
You have to be active in sharing your content through all channels including advertising. Provided that you have quality content it is not a guarantee of popularity. You have to work on that as well.