Making a dent in the publishing industry is not an easy task, especially if you are an independent author. One of the major drivers of book sales is "exposure". Great content or not, if your work is invisible to the masses, then your bottom line will remain low. Now, you might just be one of those people who love to write for the experience of it all, because it's your "passion". Kudos to you! But if you are like most authors, then you probably wouldn't mind if your "passion" creates a lucrative relationship with your pockets. One of the ways to ensure that this happens is to create exposure for your work!
To gain a little more exposure for your book, you might want to consider having it reviewed and featured on book blogs or blog tours. Next, consider drumming up a little book buzz by hosting an online author chat, book giveaway, or release party. Try to tour local libraries and book hubs. Sign up for vending opportunities at book conferences or other events where you can promote & sell your book. Book awards are nice as well. If you are able to find an award that fits the genre of your book, go for it. The goal is to exhaust as many avenues as possible that will gain additional exposure for your book. Lastly, don't settle for a one book wonder. Think of writing as a lifetime goal. Most successful authors are successful because they have a catalog of books. When you find your audience, keep giving them more. And just maybe, your passion and your pockets will align.
Happy Writing!