Get to know who you really are

You should decide what kind of author you really are, what's your favorite genre and in order to decide that, you have to start by reading a lot

We are different people. We are different authors. It takes people ages to realize what kind of author they are. Because, trust me when I tell you that it's not that simple as in 'You can write whatever you enjoy reading'. 

Most of the people CANNOT write what the enjoy reading. So, yeah it's completely different. 

Select your genre

You are what you read, so you have to realize what genre you enjoy reading the most because that defines who you actually are whether a romantic author, horror author .. etc. And helps you cut the failed attempts of a book, because once you know what genre suits you the most.

You cannot write something that you don't enjoy living. Or reading for that case lol. You gotta filter the options first. And then you have to start writing small pieces of writings in the last genres that have been filtered out. You read those different pieces of writings and you weigh your options (You might ask for external help at this point of your writing route).