Working inside a circle can be very powerful because your intent is so focused. As your magickal skills become more powerful, your need for so much ritual will decrease and you will find that your intent is becoming   powerful on its own.
I myself work with visualization and candle magick, which is about all I need. Since I am a solitaire, this is what I prefer. Working within a Coven would  be another story.
But I will go ahead and give you some basics of casting a circle. This is just one way, there are many ways to cast a circle. Some a lot simpler.

(Includes material from The Charge of the Goddess by Doreen Valiente)

Calling Quarters

(as you face the East) say: Ruler of Air, we invite Thee to join with us. Be thou on the Wind that sorts wheat from Chaff.

(as you face the South) say: Guardian of the South, Ruler of Fire, we invite Thee to join with us, Be Thou as the Flame that consumes the chaff and warms us at Harvest time.

(as you face the West) say: Ruler of Water, we invite Thee to join with us. Be Thou as the wine of harvested grape that warms the Heart and inspires the spirit.

(as you face the North) say: Guardian of the North, Ruler of Earth, we invite Thee to join with us. Be Thou as the field that nurtures the seed within, that shall burst forth in Spring.

(Use and Athame or Sword to Cast the Circle)

You can use anything to define your circle. Flowers, in the spring, pine in the winter. Stones or rope.

Face the East and walk clockwise until you come back to where you started. Walk the circle three times. Hold the Athame in your right hand and point it diagonally, across your body as you're walking the circle.

Say: I consecrate this circle of power to the Goddess.
So Mote it Be. So Mote it Be. So Mote it Be.
Whenever you have need of anything, once in the month, and better to be when the moon is full. Then shall ye assemble in some secret place: To these I shall teach things that are yet unknown and ye shall be free from all slavery. Keep pure your honest ideal, strive ever toward it, let nothing stop you nor turn you aside. Mine is the cup of the wine of life, and the Cauldron of Cerridwen. I am the mother of all living and my love is poured out on earth. I am the beauty of the green earth, the white moon among stars. And the mystery of the waters, and the desire in the heart of woman. Before my face let thine innermost divine  self be enfolded in the raptures of the infinite. Know the mystery, that if that which thou seekest thou findest not within thee, thou will never find it without thee: For behold, I have been with thee from the beginning and I await thee now.

Blessed Be
Hail and Adoration unto Hecate

(YOU WILL NOW INVOKE A SPELL OR DO A REPELLING SPELL)
(When you have finished)

CLOSE YOUR CIRCLE:

Close your circle as you opened it:
three times clockwise-starting at the East:

Say: Guradian of the East Ruler of Air, we Give thee our thanks and release thee:
Blessed Be

Guardian of the South, Ruler of the Fires: We give Thee our thanks and release Thee:
Blessed Be

Guardian of the West, Ruler of  Water: We give Thee our thanks and release Thee:
Blessed Be

Guardian of the North, Ruler of the Earth: We give Thee our thanks and release Thee:
Blessed Be

Say: I now consecrate my powers to this circle. We ask your blessings, O Great Mother Hecate on this Sacred Night.

(Take the athame, face East, walk counter-clockwise until you come bact to where you started) Repeat two more times.

Say: This circle is now open, yet it ever remains a circle. We give our thanks to all. Blessed Be!

(After casting a circle, relax, have cakes, cookies, juice ale etc......