I would suggest that healthy skepticism is usually the best defense against these feelings, but the Puritans of New England thought otherwise. They felt the world was a battleground between good and evil, and the Devil and his minions (human and otherwise) were out to cause trouble for the good people of New England.
To keep evil forces out of the home, the Puritans used some very simple forms of defensive magic. Local ministers thought that all magic was evil, but the average New Englander knew that sometimes you needed to fight fire with fire. If your house was under magical attack, you needed some magical defenses. These magical practices lingered well into the 18th and 19th centuries, well after the Puritans had faded away.
These practices tend to focus on doors, windows, and chimneys. These openings were obviously necessary for a functioning home, but they could also allow access to unwanted spirits or witches. I've written a few times before about horseshoes, which were one of the main ways to guard the house against attack, but there were others as well.
For example, a coin put under the door sill would prevent a witch from entering the house. This was pretty simple to do, providing you had money to spare. I suppose the symbolism here is two-fold. Coins obviously represent abundance and financial security, which are things a witch would hate. They are also made of metal, which tends to repel supernatural entities (think of silver bullets and werewolves, or iron and fairies). This type of magic is still widely practiced today. As this discussion on Snopes.com indicates, many people put pennies on their window sills. The practice is now said to be done for "good luck," but has it's origin as protection from witches or demons.
Fireplaces were central to the colonial home. Cooking was done there, and families gathered around fireplaces in the winter for warmth. While chimneys let smoke out, they unfortunately also could let evil beings into the home. People would often enclose shoes in the walls near the chimney to protect it. There is a lot of speculation about why this was done, but the predominant theory seems to be that somehow the witch or evil spirit would get trapped in the shoe and would be unable to escape.
If you were feeling crafty, you might want to carve a daisy wheel above a doorway, window or fireplace. The daisy wheel looks like this:
|From a church in England.|
So again, if you really, really think your house is under attack by evil forces you might want to try some of this magic. I do think skepticism is the best defense, but as the days grow shorter and colder sometimes that skepticism is hard to muster.
*****I found some of this information in Emerson Baker's book A Storm of Witchcraft, and in a few places on the web.
I hope those readers who practice Wicca or other forms of modern witchcraft realize that when I refer to "evil witches" I am referring to how witches were viewed by the Puritans and other early inhabitants of New England. I know that Wiccans and modern witches are not evil!