Today, you, the author must be the main book marketer. If you are traditionally published there is some marketing guidance. If you are self-published, devour as much as you can about marketing and promoting and put on your business cap and get out there.
Marketing and promoting take time. Marketing and promoting costs money. You must decide how much each of the events is worth your time and money.
School are an excellent place to promote your books, but as a former teacher, know that teachers want more than just book-promotions. So offer something else. If your book parallels any of the curriculum, state that. You can offer writing classes. If you book is connected to a holiday, make connections and book up to a year in advance to present near that time.
Themed festivals are an excellent way to market your book. If your book takes place in the Civil War era, there are many Civil War reenactments throughout the summer. If you wrote about dragons, Renaissance Faires are a perfect outlet. One consideration here is the vendor fee. They can be low ($35/table) or high ($175/table), and there are usually specific requirements of tent size. You must be prepared for both wind and rain. Be prepared! Visability of author and book are important, but breaking even on the event is good.
A book signing, either by an individual author or a group, can be an event unto itself. You can do this at various book stores, or libraries, or gift shops, or cafes — in as many places where books are sold or read. Many times the stores will take a 40% cut of sales and require you to do all your own advertizing. Straighten out that business cap.
Wherever I go, I set out not only my books, but business cards, bookmarks and a QR tag or code which can be read by a phone and takes the reader directly to where they can purchase books. Oh, and usually wrapped candy.
There are many other places to consider besides the ones listed here, like dog shows (if your book has a dog in it), local book clubs, museums, women’s organizations, Scouts, etc. You are a creative writer. Learn to be a creative business person. Good luck to you in the marketing and promoting of your book.