I do that too - typically have half a dozen titles before one sticks. And the one that sticks is always perfect.>I jot it down in a list.
This, definitely. The more I write, the longer becomes my lists -- not only for story titles but also character and place names. I collect them.
Don't sweat it though... as your book evolves you'll have a far deeper insight into what matters (what your book is actually about) and that's when the best title will occur to you.