Life is uncertain. If you turn on the news, you will be subjected to a constant barrage of All the Horrible Things. But even beyond that, there are always things that can harm us, whether they are acts of nature, acts of man, or just bad luck. There is no way we can keep bad stuff from happening once in a while, but it never hurts to do a little protection work to give yourself and your loved ones a bit of a boost in that direction.
I try to do serious protection work for my house and property at least once a year, in the fall as I am shutting things down and closing up the house for the winter. The coming week, leading up to Samhain on the 31st, is a perfect time for these kinds of rituals and spells (although they will work any time, of course). The darkness is closing in as the days grow shorter, and with the veil becoming thinner, it is always a good idea to reinforce your defenses.
I have full protection rituals in
Circle, Coven & Grove (that one is focused on making a protection charm for your home) and
The Witch's Broom, but if you want to do something simple and subtle, you can try this.
Take a bag or bowl and place in it some salt (sea salt is best if you have it, but even table salt will do), dried or fresh rosemary, basil, and sage (you can also use bay, juniper, and garlic--although I'd save that one for outside work!). If you want to, you can place a protective stone like red jasper or black onyx in the middle of the bag/bowl, and reclaim it afterwards. For extra oomph, you can leave the mixture out under the full moon beforehand, or bless and consecrate it for magickal work, but that isn't absolutely necessary, since most of the power from this mini-ritual comes from your focus and intent.
If you are in an apartment or don't want to make a mess, you can always dissolve the salt in water and put the entire thing into a spritzer instead (you can even use essential oils instead of the herbs if you like).
I walk around the outside of my house and the perimeters of my property, paying special attention to any entrances (including the mailbox). As I walk, I sprinkle small amounts of my protection mixture and say something along the lines of this: My home is protected. My property is protected. All those who live within are protected, from all acts malicious and accidental, from any who would cause harm or damage. My home is protected. I am protected. With the aid of the god and goddess, with the power of the earth, air, fire, and water, my home is protected. So mote it be. (Repeat as you go.)
There are no "right" words. Just say what comes from your heart, and focus on your intent to wrap your home and all those who live within in a cone of magickal protection. Then put the rest of your mixture away until the next time, feeling just a little safer and more secure in a dangerous world.