As I write, I will think of things or a certain phrase will jump out at me and I will paste it into another document or write it on my handy dandy, always by my side notepad. When the work is completed, I make a list of the things that would make a person want to read it and the cause behind those reasons. Then, I will make a list of words that can be associated with the reasons.
When I think I am close I will contact a couple of friends on my Skype program and brainstorm with them until I have come up with 3 - 5 titles. I ask people on my newsletter list if they would care to be research assistants for me. I randomly pick about 20 of them and send the list. Just above the list is a statement; 'Which of these books/articles/stories would you want to read most - least?' Of course they are all the same work but each title makes it seem that there is more than one.
I list the titles with a short synopsis under each. When I have gotten all the queries back, I compare them and my title is picked for me. It works out pretty well. You can also use friends as your query aides.