Anthony, congrats! The biggest mistake you can make is not getting accurate contact information from the guests who show up. One trick I use very successfully is printing out individual "guest sign-in" cards. I print out two on a letter sheet of thick card stock so each card is 8.5 x 5.5 in. I have found that each customer is more likely to fill out the card than put a lot of information on a single sheet sign in sheet.
Also, don't follow people around, make sure you make yourself available but make people seek you out for information. Sometimes I don't give a property flier out until someone specifically asks for it, because many times buyers run to it and hide behind it as a way to avoid talking to you.
Finally, know which alternatives are available for the guests to see and suggest that they go to specific properties at your direction. This makes you seem knowledgeable about the market and selfless in your advice.