Let's Talk About The Author's Journey

My first book, Southern Cross, falls under Historical Fiction. It is a spy/murder/mystery that takes place in 1938 and 1939. The journey from writer to self-published author has been long and interesting for me, but not without its potholes. I am beginning to see that promoting my book is going to be more difficult than writing it. Southern Cross is listed on Amazon in England, Germany, and France. So far one copy was sold in England. Nice, but how did they find me and how do I reach other potential readers? I have a webpage, listed on page one of a Google search. I just started a FaceBook page. So far I have been able to do it all myself and would like to keep it that way. What methods have worked best for you?