I kept a migraine diary for a long time and it CAN help tell you things about your headaches. I recommend, though, that you use a diary that also includes what you ate every day, if you are having your menstrual cycle, and how much sleep you got. Another big factor is chemical sensitivity. You may want to also pay attention to any reactions, even subtle, that you may have to shampoos, smoke, fragrances, cleaning supplies, etc., as conventional docs often overlook this very important contributor. If you can't find a diary with these features, you might want to make your own like I did. The more information you can gather about your headaches, the closer you can move to the solutions that will work best for you. I went from being totally disabled with migraines to almost never having one now. There IS hope, and tracking your headaches and the circumstances around them can help.
I am now writing a book on what I've learned on my journey with migraines and want to be sure that I have addressed peoples' greatest concerns. If you (and other readers) have a few minutes, I would be very grateful if you would be so kind as to fill out my very brief survey at http://migrainesurvey.blogspot.com.
Blessings, and good luck to you.