The Internet is an information treasure trove. People typically turn to it to learn something they don't already know. You may have noticed that most of the ads and solo emails you get from vendors are offering white papers and Webinars. So, it stands to reason that your prospects may be attracted to documents and Webinars on your topic or subject of expertise. Offering discounts on services and products doesn't work as well because these readers aren't in buy-mode, they're in information-gathering mode.
You know your mileage may vary, depending upon your target audience and the venue in which you advertise. But our point here is to examine closely the vehicle in which you advertise and what sort of offers are apt to meet with satisfying response rates. Think about the modality your audience is in when they see your message, be it a newsletter, a solo email, an advertisement within an email newsletter, a website advertising banner, etc.