I prefer emails and PMs. This way, you can respond in depth - at any time of the day. I am always flattered and impressed when I receive an email from a gentleman who takes the time to introduce himself, and writes a well written email

PMs are also good... but with the limited space - there is only room to type so much.
However, I always require booking confirmation to be done via a phone conversation... to see if the voice/conversation matches the tone of the email.