As practice shows, the science of SEO promotion in the search engine is not very simple. Since each system has extremely many different algorithms for ranking sites (sorting in the search engine results), none of the specialists can be 100% sure of the results of their work.
Search promotion is so fast growing and changing that what's up today may not work tomorrow. One thing is certain, if you want your site to be in love with the search engines, it should love the users. Developers in one voice say «Do sites for users and they will love and search engines.» Everyone understands that google, yandex, bing and other search engines are not live people and they can not come in and evaluate the quality of your site and they do not need it. They learn about it through «behavioral factors» and a number of other signals from living users.