In my estimation, titles should be simple in fiction. You want to grab a reader's attention, not bog them down with details. The title needs to be attractive and eye catching, but also intriguing or even shocking, perhaps. It should sound good when spoken aloud and it should have some kind of emotion behind it. And it absolutely should make you ask a question.
A really good title will undergo a metamorphosis or sorts as the reader works their way through the story. When they begin the tale, the title will have one meaning. But by the time they've finished the book, the title will mean something else entirely. A powerful title will evoke emotion even as the reader closes the book at the end.
So how do you choose a title? That's really up to you but there are some things you should consider. Perhaps you wish to name your book after the catalyst in your novel. The catalyst is the thing that is the reason the entire story starts. The inciting incident, if you will, but it does not necessarily have to be an event. It can be a thing or person. Sometimes there is more than one catalyst. It may also be the goal. think about the novel The Sword of Shannara. The title is basically the catalyst. It's the reason Allanon recruits Shea Ohmsford in the first place. If you know nothing of the book, seeing that title will make you wonder what this sword is and why a guy or girl named Shannara might be important. The story answers this question, but you leave the novel feeling quite differently about the title. It's an effective title.
Perhaps you'd like your book title to have an aura of mystery. In this case, try a single word or phrase with a defined meaning. Think of Twilight. By now, everyone knows exactly what the book is about. There's little mystery to it. But imagine you knew nothing about the book. What is twilight? A time of day. Nothing more than that. By the time you've finished the book, however, it's far more than just the time between full dark and sunrise. Whether you like the book or not, the title is effective.
Other novels have titles that are either based on a familiar phrase, a play on words, or even a puzzle. You can use irony in your title, perhaps an irony that isn't revealed until later in the story. For example, a story called Road Trip seems like it would be fun and exciting and full of unexpected adventures and hilarious moments. But what if it wasn't? What if instead that road trip turned into a horror show? Taking something benign and turning it on its head is a great way to find a title for your book.
However you choose to title your book, you should try to make sure that your climax, denouement, and title work together in some way. It will give a further cohesive nature to your novel. Even if you start with a title you think works, be open to changing it. Make it work for your story. You may have a wonderful title, a title you love and cherish, but it just won't work for the story you've got. So shelf that title and come up with a new one. The old title isn't going anywhere. You can always use it for another story, one it fits better. You don't need to be protective of a title. It's just a title. It serves a purpose.
