You likely send out a great number of emails every day. Make sure to include a link to information about your webinar event or even the page for people to sign up. By doing so, this link will appear at the bottom of every email you send, attracting the attention of more people who may not receive your original email blasts and notifications, especially if recipients forward the email. Furthermore, make sure you highlight the webinar/webcast link and corresponding text in a different color so it really stands out. Once an event has ended you can remove this link and replace with one for a future event.