I don't know about you but in order to streamline things I have a "Open House Kit". It's almost everything I need for an open house and I put it in one of those small rolling suitcases. I have pens, sign in sheets, a clipboard, extra copies of my business card, a calculator, tape, air freshner (you never know when a house is going to smell), a flashlight, extra batteries, and some office supplies.
Also if I, or another realtor in my office have a property nearby I come with a stack of directions from my open house to the other house. I don't leave them out, but have them handy if I think a client is going to like them better. It's easier than writing out directions every time and helpful if I can't remember the address or directions.
I learned an important lesson at a recent Open House. It has been hotter than hot lately in California. I went to do an open house without water. With average daily temperatures over 100 degrees I will never make that mistake again.
DON'T forget to bring water! Offer water and even popciles or ice cream as a way to beat the heat. Show potential clients that you had them in mind even before they had you in mind.