Craft projects, bulletin boards, or other activities related to an author's books can really generate excitement for author visits. One idea is to have each student illustrate a favorite scene from a story. Display the author's books in the school library. If the author allows time for questions and answers, have the students think up questions ahead of time. Sometimes it helps to have the questions written out.
Name tags are helpful to the author when answering questions or while autographing.
Consider book-signings along with author visits. Students who have connected with an author will treasure having a signed book to own. You can order books through a local bookstore. They will usually allow schools to keep a percentage of the profits as a fund-raiser. Or order books directly from the publisher.