incoming links
Start by signing up for HARO, Help A Reporter Out. This is a free service that links expert sources (like you!) with journalists looking for contributors.
Because I had added value twice to their site (once by letting them know about the outdated link, and again by showing my valuable resource), people were happy to add my link.
And since I added value to their website twice (once by giving them a heads up about their old link, and again through my valuable resource), they were more than happy for me to add my hyperlink to their page.
Google interprets backlinks received from websites you don't own as telling it to "Hey! This website believes that the other website is trustworthy. This helps to rank the site, especially if it has a high level of domain authority.
social media
How to get backlinks