Every author I know and read says that their marketing takes up much of their time. I can agree to that without reservation. Every one of the blogs, newsletters, and websites I follow are discussing marketing as we approach the bloated commercial season that begins the end of this month.
I don’t know what has worked for you, but the only thing that has worked for me is word of mouth. I have given away about two thirds of the printings of my books and even the really commercial books (Westerns and other fiction) have slowly, very slowly been getting read and reviewed and then beginning a market.
One thing that has really helped is donating copies to my local library. I live in a small town of basically non-readers. BUT, the word has gotten out that my books are in the library and due to being a local boy the library leaves them on the new books shelf for a longer time than all them high dollar books written by them foreigners. Word of mouth is causing them to be checked out frequently. Those who like them have bought personal copies and gift copies.
Read a book, tell a friend.