Guest speakers are one of the main attractions at a conference, graduation ceremony, special event or meeting, and the best ones are usually booked well in advance. Event organizers need to invite their guest speaker of choice at least six months to one year in advance of the date of the event. A formal letter of invitation ensures that the organizer and the speaker understand the requirements of the event.
If the idea is to attract more attendees, a famous personality may be a good choice for a guest speaker. If the event is focused on a certain aspect of business or technology, a speaker who has particular expertise in the field may give valuable insight to attendees. A highly regarded guest will add prestige to the organization. Whatever the theme of the event, the speaker should be suitable for the event and the audience.