Hey this is Tikka. Today I have a simple way to protect your house from supernatural forces. This is really meant for "houses" not "apartments".
All you need to do is get ahold of a plant known as "Angelica" and plant it in a garden around your house. It's used for protection, so this can work as a very weak barrier. This plan I would use to back up a stronger warding spell.
What I would do for a warding spell would be to get bay laurel and bay leaves, mash them together in a mortar and pestle, and then burn it as you walk around your house, and chant a simple spell something along the lines of. "By bay laurel and leaves I banish all evil from this house, may it never come in again." Both bay laurel and bay leaves are used for protection and to banish negative energies. So hopefully this will help those of you who believe in Wicca. Those of you who don't... good luck and hopefully you can find something else that you believe in to protect yourself.
Forever Watchful~ Tikka
Edit: so there's no confusion, what this means is use the WHOLE bay laurel plant, leaves and all.