I thought this might be a fun and interesting thread to add; a bit of folklore associated with our homes, doors, and such.
The main entrance to the home has always been considered a very magical location. Household spirits are thought to dwell there, and it is considered a protective area because it blocks out the outside world.
To increase the magic and protective vibrations, cleanse the area around the door. Remove all dust and cobwebs. Once done, sprinkle salt around the area. Sweep the area in front of the outside of the door with a broom to further remove negative energies.
You can add more protective energy by planting ferns, and red geraniums around the entrance to your home.
The door has always been considered a threshold of power within the home. It is both an entrance and exit to the home, thus is has been considered a place of protection and a portal to other realms. The following are a few methods that can be used to strengthen the magical properties of this threshold of power, and by doing so increase the magical vibrations of your home itself.
If you hang a gourd on both sides of the doors in your home it will keep away negativity. Placing a piece of bamboo or a wreath of both leaves and thorns will do the same. If you draw a circle on your doors with chalk it will keep away ghosts. Hanging garlic or dill over your doors will prevent anyone that envies you or wishes you harm from entering. If you hang a sachet of bells or salt from the doorknob it will keep malevolent spirits and entities away.
Painting your doors blue or crossing two needles and placing them under your doormat is said to also protect your home, as is placing ground mustard seed or dragon's blood on your doorsill and then hammering nails into your door in the shape of an upright triangle.
Certain herbs can also be grown in pots on your porch to help protect your home. These include: ferns, lilies, marigolds, and juniper. A sachet filled with salt, sage, mullein, tansy, and other protective herbs can be placed beneath the porch to keep ghosts away.
Placing five shiny pennies under the porch is said to bring money and love into the house.
If you would like to see ghosts, at dusk or midnight stand at a doorway in the dark and look into another room. You need to have the door half-opened. Place your cheek on the door and look past its edge. You may see spirits or strange shapes. This is believed to be caused by the fact that the door is considered to be a portal or entryway to other realms.
Meanwhile, if you would like to rid your home of ghosts, slamming your door in quick succession several times is said to help send them away.
Sources:
The Magical Household: Spells & Rituals For The Home ~ Written by Scott Cunningham and David Harrington
Llewellyn's 2011 Witches' Spell-A-Day Almanac ~ Create A Magical Threshold ~ Article written by James Kambos