When you create content, refer to links that point to reputable sites in your post. It could perhaps be something that enhances the information you are writing about. If possible approach them and mention that you find their content extremely useful and that you have linked or would like to link to their content. This is a great opportunity to build relationships with the blog owners as well. They may even return the favor by linking back or promote your content if they find it good.

Basically, this is like approaching them for trading links or for something in return like social media share. They could be free or sometimes for a fee as well. Links are of two types Do-follow or No-follow. Do-follow links are created by default and No-follow links are those that do not pass link juice. It signals to the search engines that you do not endorse the site, and so are not passing the SEO value in that case. They are usually created for sponsored posts.