I will talk about such methods of promotion in the English-language Internet, which are rarely used in RuNet or not used at all.
For example,working in cooperation with journalists, you can get quality links from well-known websites for free.
In most cases you cannot get links by other ways.
In RuNet, almost no one uses multi-level links. With this method, the links are placed in several levels. This method allows you to get greater effect from the same number of links.
Getting links using Scholarships - this method is popular in English-speaking countries and allows you to receive links from educational sites in edu domain zone. Such references give good trust. Not every site has links from websites of colleges and universities.