Difficulty: Average
Time Required: Varied
Here's How:
You'll need a white candle, a cup of water, a small bowl of salt, and incense. Each corresponds to one of the cardinal elements and directions:

North/Earth: salt
East/Air: incense
South/Fire: candle
West/Water: water

What You Need:
Incense
Salt
A candle, preferably white
A cup of water
The tool to be consecrated

If your tradition requires you to cast a circle, do so now. Light the candle and the incense. Take the tool or other item you wish to consecrate in your hands, and face north. Pass it over the salt and say:

Powers of the North,
Guardians of the Earth,
I consecrate this wand of willow (or knife of steel, amulet of crystal, etc)
and charge it with your energies.
I purify it this night, and make this tool sacred.

Now, turn to the east and, holding the tool in the smoke of the incense, say:

Powers of the East,
Guardians of the Air,
I consecrate this wand of willow
and charge it with your energies.
I purify it this night, and make this tool sacred.

Next, face the south and pass the tool over the flame of the candle -- be careful if it's a flammable material like Tarot cards or a robe! -- and repeat the process, saying:

Powers of the South,
Guardians of Fire,
I consecrate this wand of willow
and charge it with your energies.
I purify it this night, and make this tool sacred.
Finally, turn to the west, and pass your ritual tool over the cup of water. Say:

Powers of the West,
Guardians of Water,
I consecrate this wand of willow [or knife of steel, amulet of crystal, etc]
and charge it with your energies.
I purify it this night, and make this tool sacred.

Face your altar, hold the wand (athame/chalice/amulet/whatever) to the sky, and say:

I charge this wand in the name of Old Ones,
the Ancients, the Sun and the Moon and the Stars.
By the powers of the Earth, of Air, of Fire and of Water
I banish the energies of any previous owners,
and make it new and fresh.
I consecrate this wand,
and it is mine.

Now you've not only consecrated the tool, you've claimed ownership. In many Wiccan traditions, it's considered a good idea to put the item to use immediately to bind the consecration and strengthen the energy of the tool. If you've consecrated a wand, athame, or chalice, you can use those in a ceremony to consecrate another tool. If you've consecrated something that is worn, such as an article of clothing (for example, a ritual robe) or a piece of jewelry, begin wearing it now.