What should seo expert should do?

Hi friend, The main aim of the seo expert is to get the website top position using on-page and off-page optimization and link building. Other than this concept can you tell me new techniques to upgrade website. And also how to use social book mark sites and networking sites. I dig once by just adding website link. That's it ? what should be done after. Our website should need of backlinks what should be done. Only serious replies pls, you can also provide good reference websites. Thank you friend