External factors ’ peculiarity is that they are very difficult to change (in some cases impossible). One of the main factors is the number of links that lead to your site.
Search engines count not only general link amounts but their quality too. Links received from authoritative sites (for example, The New York Times) have greater weight. Links received from public institutions, non-commercial organizations and university sites are able to positively influence the site’s location in the SERPs.
There are many parameters when evaluating the links search engines count: what keywords and phrases they include, whether they are similar to the subject of a page they are placed on and a page they point to. Other links placed around your links are also counted. If the link is located in one block with other links, search engines can consider them as paid ones. That`s why it`s better to place the links in offers. Offers??? I don’t know what you mean here, others might not as well.
The links also have to be natural. Participation in link exchanges, link spam and other means of promotion can lead to punishment or penalty.
Link growth has to be gradual: sharp surges of links growth can negatively influence the site’s ranking.