Don't pitch too soon!
The poor salesman always pitches too soon. I'm reminded of this from a small conference I visited where the poor, unsuspecting punter innocently asks "so what do you do?" and gets bombarded with a 10 minute sales pitch. When you're approached in this way, have a prepared sequence of questions to help you qualify.
e.g. "What business are you in?" "How do you cope with XXX?" "What plans do you have for upgrading your XXXX?"