You’re already a big winner when you’re in front of your webinar audience. Participants were interested enough in your content to register, hold space on their calendar, then show up attentively to your webinar. They have self-qualified themselves as being in the market for the type of product or service you offer, and think you’re the God of SEO (or whatever your schpeel is on).
For example, if you’re hosting a webinar on how to use WordPress blogs, and participants are asking a lot about increasing traffic, you could position your email like this: “I’m getting a lot of questions about boosting traffic to your blogs, so I’m throwing in a bonus how-to guide which will be sold later for $97, but you’ll get it free if you act now.”
Create a presentation you can deliver which is related to that product. The presentation should be helpful and useful, and mostly pure content. If the webinar is going to be an hour long, then you should have at least 45-50 minutes of good, solid content in there before you ever even talk about the product. An exception would be if the entire point of the webinar is how to use that product.
Then you ask them follow up questions to make sure they understood your presentation, what they do not understand, what objections they may have, etc. etc. You will close more sales if you are able to get feedback from clients, and Webinars allow you to see their face, to hear their voice to know how they are feeling about you, your presentation, your company and your products and services.