I find:
If they ask questions AFTER booking then they haven't read my profile and they are most likely to cancel.
Those that send loads of messages - even if they aren't questions, they are just chatting - well, I generally don't reply at all - who has time for that?! But if and when I do reply it is just short and professional and I will always just refer them back to my website.
I don't chat at all, but I also don't cancel.
Surprisingly, they sometimes turn up anyway, even though I haven't replied to their many messages!