Your real estate agent (if you have one) should lead the open house, but you may want to offer
support. Make the property as inviting as possible and make sure that your agent knows what you want to highlight.
It is not your agent's job to clean the house and make it presentable. It should be that way on the day of the open house before the agent arrives. Trash should be taken out, dishes put away, the lawn mowed and the snow shoveled.
Once you communicate the proper information to the agent, you should leave. Buyers want to see the house, not you. If you are following them around in an attempt to be helpful, you will most likely make them feel uncomfortable and they will leave before giving the house a chance.
If you do not have an agent, then make sure to promote your open house every place you can, but especially concentrate online and with signs. Tell the neighbors and try to make specific contact with the target demographic. Use social groups, schools, houses of worship and other specific places.
On the day of the open house, act like the agent, not the owner. Be helpful, but not too anxious. Show highlights of the house and answer questions thoughtfully, but give people space to really consider and appreciate the property. Be available, but don't follow them around unless they ask.