One of the more difficult link building strategies is the one with webinars. When you already have a following it might be easy to have thousand people join your webinar, but the difficult is to have them share a link to your site.
Webinars for SEO and link building
Only use this strategy when you are able to invite over 100 people. When you are lucky there will be a 20% success rate of sign ups. That means 20 out of 100 might sign up.