How Do You Write a Book on the Side?

Don't write about something that you're not familiar with. Don't write a long book, the more people can get done in a shorter period of time. Write it in public to show your commitment and make sure they know you are serious. If i don't tell people i'm writing a book, and then i just launch it last month, maybe i would get three sales because people need time to warm up to what you're doing.