Step back from the book and do some brainstorming about your novel's contents. Think not only about the plot and protagonist, but also locale and any interesting elements that may be noteworthy and catchy.
Compile a list of keywords and look for links or intriguing concepts.
Explore the possibility of using known phrases or quotes, but not ones that are too familiar. Finding the right balance between being recognizable without tottering into cliche can be the difference between a memorable or forgettable title.
Consider titles that are loaded, such as phrases that are ambiguous, have multiple meanings or sinister overtones. These puzzling or aggressive phrases can lodge in the mind of the reader.
Keep the title short. The more memorable the title the better chance for success.
Ask friends and colleagues for comment or ideas. The more people you can get feedback from the more likely it will be that you will find a winning title.