Once you are done with your storyline, go over it again. Look at the story from different angles and most of all, ask yourself two main questions with every part of the story: why and how? Why would a character go somewhere or do something? Any problem with validity of behaviour can be quickly caught and corrected via this process; definitely faster than in the manuscript.

Be hash and brutal, but don’t waste too much time with this part of the process. The storyline is just one possible way of telling the story, and it’s definitely not the final version. The story will change once you start writing the manuscript, but it’s good to know where the story’s heading.