If you wishing to contact me for professional reasons, please do so via my agent, Fran Bryson, or publisher, Hachette Livre. Just look on their websites for their email address.
If you don't find the answer, and you don't mind asking your question publicly, head over to Twitter. I check it once a week and answer all reasonable questions asked of me there (but I don't tweet much any more).
I have an Instagram account that I check everyday (when not travelling) but it's not a great format for answering questions. My Facebook fan page is run by my publisher, and I don't think they check it for questions, but you can try.
If none of those options suit, give the following form a try: