You may think that the only way to help an author that you like is to buy their book. There are many other ways to support authors. Here I will give you a few thing and I would love if you added more in the comment section.
Independent authors need to not only write but promote themselves. That means the more time they spend on promotion, the less time they are actually spending at their craft. I actually like social media so I like creating and promoting using social media.
Borrow a book from a local library
The more you borrow a book the more a librarian may realize that they need a second copy of the book or suggest the book to other librarians.
Like the Author on Amazon
On the right top corner of an Amazon author page is a like button. Others will see that you like that author and may read further on the author page.
Share Author Posts on Social Media
Many authors have twitter, pinterest, facebook, youtube and more. By viewing and sharing these posts you are helping the author out.
Leave a review on Amazon. An honest review, even if it is not 5 stars will help out the book and the Author.
Chat With Author
Emailing, or talking though social media to an author excites them. You can even talk to them at a book reading. They will get excited that their message is getting across. This momentum will keep them writing and thinking of new things. Your feedback is very helpful.
Put a Book on your Good Reads Shelf
Good reads has become a popular place to rate books, add them to your book self, and share them with your friends. Add the authors book as “want to read” or rate the book.
Download a Book on a Free Day
Many books are offered for free to promote the book and to raise the ranking on Amazon. By downloading the book the book is more likely to be seen by others on free and non-free days.