Since this is a housewarming, you need to make sure that your house is clean and immaculate. You're, in a sense, "showing it off" to people, so they will want to look around. Do you want to guide people or have people look around at their leisure? Make sure valuables are put away and doors to rooms that you want no one going into are shut and locked. Make sure that every room and the outside is clear of debris, as well; you don't want people tripping or falling. I know you think you'll have trusted friends and family over, but people everywhere can be jerks.
Set out appetizers on your table, some wine or light cocktails if you wish, and show your home off. That's all you have to do.