You've heard over and over that selling books requires a robust author email list. (bookworks.com)
For more on this subject, read «Author email list lessons» and «What should I send to my author e-mail list?» (buildbookbuzz.com)
I also find some books through other sources, such as Amazon, BookBub (and other mailing lists), Facebook (e.g. the Avid Readers of Christian Fiction group), Goodreads (what my friends are reading and reviewing), and through author email lists (perhaps that's a topic for another week). (iolagoulton.com)