Send them invites for your webinars or whitepapers. Send an email regarding it, and wait for their response on it.
? Make an email list:
When you have consistent attendance for your webinars, sponsored ads and announcements can help you make money by recruiting sponsors for webinars to help cover costs.
? You can also give a preview of your webinar on LinkedIn along with a blog around it, instead of directly promoting the webinar. You can also create sponsored updates and standalone ads to advertise on LinkedIn.