Hi Bob:
Welcome to the Print4Pay Hotel!
What market are you in? Door to Door is always tough, all I try to do on the cold call is get the name of the buyer (DM) and leave a business card. I can then follow up with a phone call. You probably should have some type of flyer explaining the value of your company. You bring instant credibility to table by being a service engineer. Use that to your advantage. I have more but would like to see what others have to say also.