When you decide to use link building, you need to know how to do it well, and with whom you should link. First, think about building internal links that can help you connect your whole site. You should make a keyword research to have many keywords suggested, which have to be both relevant and popular.
Also, you cannot just add any keywords randomly. You need to do it wisely, assigning the right content to the keyword, and creating a search-friendly information architecture. And, once you have this, you can begin linking your pages with your selected keyword.