Open houses can be a way of gaining buyers Always have a signup sheet which asks for emails and if they are working with another agent then call that agent 

Getting people to the open house sometimes needs some thinking. There are buyers who go to open houses for sport and free food. In certain areas nobody comes. Even agents who you need to see your listing don’t. I have offered lottery tickets and a contest for any agent to guess how much the house will eventually sell for to lure agents.

Have a lender Or title company sponsor an open house and have them promote it as well 

Connect with open houses by other agents at the same time and cross promote so you can get the traffic of all of their contacts too. 

And always have others with you for safety