Okay, the items below are optional, I have cast circles with just my hand, and nothing else. However, I am going to share the formal way to cast circles, using my favorite circle chant from Embracing The Moon.
- Athame (ritual knife)
Before casting your circle you should first cleanse the area where your circle will be from all foreign and non beneficial energies. Taking your broom sweep just the floor(does not matter if you have a rug our you are outside)- the idea is that you are sweeping away the energy not the debris.
Then place a few pinches of salt into some water and sprinkle the salted water around the area where you are going to cast your circle, Say:
With this holy water I do cleanse this space from all negativity
and energies that do not benefit me
Now that the area is clean and clear take your athame or you can just use your hand, starting at the east walk slowly clock-wise around the perimeter of your circle while speaking:
Three times ’round i cast my blade
that this circle shall be made
first white crescent from the maidens brow
her strength and independence be here now
second red blood from the mother womb
as i weave my life on her starlit loom
third black shadow from the crones abyss
teaches me wisdom with her underworld kiss
sacred space within this circle now lies
protect me from unwelcome eyes
let no one enter here within who has not been made welcome
this is my will so mote it be. 
Your magickal circle is now cast! Once your magick circle is cast you may not exit this magickal space, if you do the circle is broken and you must re-cast the circle again. When your magickal working is complete then you must release this magickal circle
In my own practice I walk around counter-clockwise 3 times while seeing the magickal circle slowly fade away:
This circle is open but never broken.
You can re-cleanse your space by sprinkling salt water over the area again or sweeping the energies with your magickal broom, this is useful if you are working on more “darker” work such as; banishing, hexing, or deep cleansing work.
In the beginning of my magickal practices I cast my circle several times a week to get in the habit of just doing this practice, to know what the energies felt like and to practice this art.
 Galenorn, Y. (2005) “, Embracing the Moon”. Llewellyn Publications. St.Paul, Minnesota Pg. 51.