Open houses are not just an opportunity to showcase homes to propspective buyers, but are often attended by people thinking of selling who are coming to check the agent out, and the competition.
Walk the neighborhood with flyers the day before the open house. Knock on doors and talk to people! Invite them to the open house. Know the competition in the immediate area so when someone asks about the home for sale down the street, you can amswer without having to "look it up".
The extra effort sets you far apart from the competition.
Get there early (never be late), and put up flags/signs so it is clear the home is open. Use as many directional signs as possible as many people looking for a home spend time driving in the areas they are considering.
When people come in, I simply treat them the way I would want to be treated, and talk with them in a laid back (professional) manner. I'm there to answer thier questions and give them information on the home, neighborhood Schools etc... I am there to help! Always have some statistics ready in your head like average sales price, what the numbers are for last month compared to a year ago, average days on marketg etc... And I always ask them to sign in. It is prudent to have a list of who attended the open house not just for your records, but the seller as well. If they already have an agent, respect that.
Ask them if they would feel comfortable with you following up with them, and always send a thank you note for coming to the open house.