2. Don’t worry about marketing until you have something to market.
I know it’s hard to hear, but one book is not enough. To get a good return on your investment (ad-spend and time-spend), you need to be able to sell yourself as an author and then keep your readers hooked. Getting one reader to read one of your books is expensive, and isn’t going to pay off. Spend your time developing your inventory and getting reviews before you you spend your heard-earned cash on marketing.