Send them invites for your webinars or whitepapers. Send an email regarding it, and wait for their response on it.
Once you have recognized these leads, nurture them with follow up through various modes like emails, phone calls, e-newsletters, postal mails, etc.
Provide a short video to describe the benefits and what people will learn through your webinar. You can put it on your website, social media, blog and emails.
After making a comprehensive layout for your webinar, the next thing you should do is promote it. Using social media, Facebook ads and LinkedIn groups are examples of advertising platforms which you use for your marketing campaign. There is always an extra chance of capturing leads if you pay more attention to your promotional strategies and advertising.
It is really difficult to get an audience to be a part of your webinar. You always need to look for a topic from your niche that is trending to be able to capture the attention of a large audience. Do some research and look for customer problems. Be relevant and informative with your webinar topic to encourage more people to attend your webinar.