This is the way I cast a circle, if I'm doing a full ritual, which isn't that often, because most of the time I just do my own private meditations on the Sabbats, and don't do a lot of spell work (I follow Wicca more as a religion/belief system, I do perform workings, just rarely, and it doesn't form the main part of my practice). Anyway...
I dispense with the traditional measuring of the circle with cords, for the majority of people practicing in the privacy of their homes it's just not practical to have a circle 11 ft in diameter at it's outer most point.
First I consecrate salt and water. I trace an invoking pentagram 3 time in the water with my Athame, and say the words -
"The blessings of the Lady and Lord be upon thee , o spirit of water, I do cast out all impurities and darkness so that only goodness and light remain."
I repeat with the salt, saying the same words ("The blessings of the Lady and Lord be upon thee , o spirit of water, I do cast out all impurities and darkness so that only goodness and light remain").
Using the tip of my Athame I then mix three measures of salt into the water, and spend some time in quiet meditation visualising any negative energy being drawn into my body with each breath, and then dispersed into the earth. At the same time I also visualise cleansing energy from the earth being drawn into me and channeled into the water as white light. I do this until I'm satisfied that the water and salt mixture has been properly purified.
I then take the consecrated water, and walking in a circle, starting in the east, I sprinkle the water around the area I'm working in, and say the words -
“I walk this circle once around to bless and consecrate this ground."
I repeat with burning incense, again walking the circle, and tracing the incense in the air whilst saying the words -
“I walk this circle once again, between the worlds all time will bend.”
I then take my Athame and trace the parameters of the circle in the air, saying the words -
“I walk the circle thrice this time for the protection of the Lady and the Lord are thine.”
I then stand at each of the directions, East, West, South, and North, and draw an invoking elemental pentagram at each point (visualising each pentagram flowing from my arm, through my Athame, and being traced in the air in front of me - I also visualise the pentagram glowing the colour of its element, and also visualise the appearance of the Lords of the Watchtower).
As I'm doing this I say the words -
"All hail be to thee, Lords of the Watchtowers of the East (repeat for South, West, and North)
I do summon, stir and call thee up that you may witness these rites, and guard this sacred circle.
Once I'm satisfied that each of the corners has been properly called, I bow my head, and kneel in the direction as a sign of respect.
Once I've finished calling the corners, I spend a few moments visualising the integrity of the circle, and strengthening it if need be. I then stand in the middle of the circle, with both arms raised above my head, and invoke the Goddess. Then I with my arms crossed over my chest, fingers formed into the sign of the Horned one, and invoke the God. I usually write my own individual invocations to the Goddess and God beforehand to do this, and it changes depending on the reason for me invoking them in the first place (healing ritual, Sabbat, etc). If I'm working with a partner or group I'll more than likely perform the full ritual of drawing down the moon, including the traditional horned god invocation and the five fold kiss. Otherwise that's pretty much it, and the circle is cast.