Here's some ideas for planning an open house:
Put a Sign in your yard on the Wednesday before your Open House such as:
Saturday 11:00 - 3:00 or whatever time you have set aside
Make up some flyers and give them to your neighbors and ask if they have friends or relatives that might want to move in the neighborhood. Pass out flyers in neighboring subdivisions or apartment buildings near you. Signs and Balloons leading to your house are very important.
If you have more than 2 Families stop by you've done a good job.
In your case if you have some help you can draw in people by advertising a Yard Sale and Open House, this way you get rid of clutter and you may find a buyer too. It's impossible to predict an open house and paying to advertise for one isn't worth it but there are some free venues for online advertising which can't hurt.
It's also a good idea to have a current market analysis and printouts of all the competition homes in the area in a presentation folder along with a copy of your utility bills, tax bill and insurance. This is a portfolio of your home and buyers are interested. Also make sure you've filled out your Sellers Disclosure form and all the disclosure forms that are required to sell your home and put them in the portfolio also.
These are just a few things I do for my sellers, it really makes an organized presentation to potential buyers and you can wow them with it at the open house.
I hope this helps you and Good Luck selling your home.