I’ve been asked what my Dumbledore’s Army of Hufflepuffs/Ravenpuffs who like Disney can do to help support me. For the most part, it’s the same things you’d do to help support any author you love, though now that my target reader is clear, you’ll know exactly who to talk to or what selling points you might be able to use (if you like this, you may enjoy this).
The big thing is to tell others about the books you love, in whatever venues you use to talk about books, whether in person or online. Recommend books to your friends. If someone asks for book recommendations that these books would fit, bring them up. Tweet/blog/post about them on Facebook. If you’re a Booktuber, do a video. Put pictures of them on Instagram or Pin pictures. For my books in particular, you could mention that the Enchanted, Inc. books are like Harry Potter for grownups. If you’re active in any kind of related fan groups online, you can bring them up in relevant discussions.
Post reviews of books you love at places like Amazon or Goodreads. In your reviews, mention these connections — “fans of Harry Potter might enjoy these books about a magical corporation.” Also mention the other things you like about them. The most helpful reviews are the ones that can help others decide if these books are for them, so the more non-spoilery specifics about what you like, the better.
You can also amplify things an author you enjoy does — like or repost/retweet/share their posts, post links to blog posts you think a broader audience might find interesting.
If you know of someone who talks a lot about books — Bookstagrammers, book bloggers, Booktubers, etc. — who you think would enjoy the books you enjoy, you can suggest these books to them.
Request that your local library carry the books you like. There may be a form available in the library to fill out, or your library system may have a form on their web site. Mine calls it “add item to collection.” Libraries are great because there are so many of them that an author can make a lot of money just by libraries buying books, plus they’re a great way for readers to discover authors. I know that I found most of my favorite authors through trying their books in the library, but then I ended up buying copies to keep for myself and bought their new books when they came out rather than wait for the library to get them. My library’s form has a spot for explaining why you think the library should add this book, and that’s where you can put stuff like “adult fans of Harry Potter might enjoy this series.” If the librarian is intrigued by your description, she may try the books herself and then recommend them to patrons.
For recent releases that are in bookstores (which mine aren’t right now), talking to booksellers about them might bring the books to their attention so they recommend them to customers. When a new book by a favorite author comes out, I like to go to the store during release week, do the happy dance when I find the book, and gush about the series/author to the person who rings me up. The bookseller may be intrigued enough to take a look at that book. If they don’t have the book in stock, you can ask them to look it up for you in the system. That also brings the book to the bookseller’s attention (and sometimes they may order a couple of copies for the store while they’re at it).
Those are probably the best things a fan can do to support an author or book. Word of mouth is the most effective way to market a book, and it’s one thing that an author or publisher can’t do a lot about. That’s up to readers.