Most important is FOLLOW UP after the open.  Have a sign in sheet and follow up immediately after and then another day or two later.  Also, have plenty of info to give out.  People love free helpful information about buying and selling homes.  Talk to them about their needs, not just the house or real estate in general.  Have light conversation.  Get to know them some.  I have a table that I set in the entry way with all of my information and sign in sheet.  I don't wait until they are in the kitchen to approach them with this information.  My method is to greet them, offer them a flyer on the house, ask them to sign in and then immediately direct them to the free info.  This takes the emphasis off signing in and makes it just seem like a normal part of the process.  Then I tell them a few of my favorite things about the house, tell them to take their time and let me know if they have any questions.  At the end of their walk-through, I ask them what they think of the house and if they love it.  Then, if they do, we talk about how much interest they have.  If they are not ready yet, I ask if they have a house they need to sell first, or what their timeframe to be ready to buy is.  If they don't think that is the house for them, I already have a printout of other homes in the same area of similar size and price to give them and offer to set a showing after the open for the ones they drive by and like.  I hope this helps.