The ideal thought leader must be prepared to offer unique insight that is relevant to the event. Once you have your expert chosen, create a story that revolves around their area of expertise, and tie it to the theme of a presentation.
There are likely a myriad of events where your experts can contribute, and it's important to keep them all on your company's radar. Also keep in mind your company's bandwidth - every company has a limit to the number of events it can participate in.
Even when everything is in place for the presentation, your work is not done just yet - any support staff who are attending the event must be briefed on the presentation and company messaging so they can answer questions from stakeholders and direct them to company resources as necessary.