Of course, there are the usual places to sell books--indie bookstores, Barnes and Noble, Amazon, etc. Those are quite obvious places to sell books. But sometimes they aren't the best places for an indie author to sell books. For one thing, they sell a LOT of books, many of them by authors who are far better known. It's easy for a first-time author (or even one with a track record, but not a lot of exposure) to get lost in the numbers. One of the best things an author can do is try to find other outlets to sell their books.
I discovered Mike Orenduff's "Pot Thief" series while visiting Gruet Winery in Albuquerque, NM. He had taken a specific detail in his series--namely, that his protagonist, Hubert, had an affinity for Gruet wines--and used it as a marketing point. To that end, when I decided to make Noisy Water Winery in Ruidoso, NM the place of employment for one of my secondary characters (and gave my protagonist a taste for their wines!), I told the owner, who also happened to be my boss, that I had just had a book published. Before he even knew what it was about or that his winery was mentioned, he offered to carry it in his store. Four books later, Noisy Water has hosted every launch party since then and carries the entire series in their store and on their website.
An author needs to take their book out of the box labeled "book" and see where else it will fit. Does it deal with a specific period of time or a particular place? Contact historical museums or chambers of commerce (some have gift shops) to see if they are interested in carrying them. Think about your story's setting. Mine is an RV campground. Many have gift shops. I carry promotional bookmarks to leave and have donated a few books (with purchase information tucked inside) to their libraries. Is there a gift shop in your area that is all about "local" stuff? They might want to carry a local author's work. Hospital gift shops might be interested in carrying books, especially non-fiction work about hope and inspiration or light reads for patients to pass the time.
And there are non-traditional places to sell books, too. Once a month, during the summer, I set up a table at our local Art Walk. This takes place every third Friday night in our city's downtown area. Food vendors, live music, and artists (writers are artists, you know!) set up booth's to sell their wares. It only costs me $10 for a three-hour spot and I meet a lot of people and sell quite a few books. What about local festivals, farmers markets, church events?
Keep an eye out for local author events where you can give a talk and sign and sell books. Is your library celebrating a milestone or promoting a cause or event that ties in with your book's topic? Strike up a friendship with librarians, Friends of the Library organizations, bookstore owners, and employees. They can clue you in to author and book events or festivals in the area and suggest other venues.
In this day and age, it makes sense to make a book stand out. It's hard to make it stand out when there are many other books around it, so an author needs to look for venues where a book will draw attention.
My own table at the Celebrate Authors event last year at the Picacho Hills Country Club in Las Cruces, NM. The manager at Barnes and Noble introduced me to the president of the local Friends of the Library organization which hosted the event. I have a standing invitation!