Make sure that other sites link to yours
Links help Google crawlers find your site and can give your site greater visibility in Google search results. When returning results for a search, Google uses sophisticated text-matching techniques to display pages that are both important and relevant to each search. Google interprets a link from page A to page B as a vote by page A for page B. Votes cast by pages that are themselves “important” weigh more heavily and help to make other pages “important.”
Keep in mind that Google algorithms can distinguish natural links from unnatural links. Natural links to your site develop as part of the dynamic nature of the web when other sites find your content valuable and think it would be helpful for their visitors. Unnatural links to your site are placed there specifically to make your site look more popular to search engines. Some of these types of links (such as link schemes and doorway pages) are covered in Google Webmaster Guidelines.
Only natural links are useful for the indexing and ranking of your site.