Circles are everywhere. Life is a circle. And so they are used in majick. Circles are cast by witches to from a barrier between the normal world and that of majick, and create a sacred, cleansed space to work our spells etc in. Circles form an area where time and space are completely irrelevant.
Circles can be different shapes and sizes. They could simply be a bubble you imagine surrounding yourself for protection, or they could be the traditional 9 foot chalk circle, with calling of guardians, spirits etc.
Before casting the circle we shoudl cleanse ourselves ritually, everytime we cast. This is becasue we are the things from which everything flows, and purity is important. It also gives more of a sense of purpose, preparation makes the whole thing more special, because youve had to work that little bit harder to make it.
However you do it, preparing for the circle is a personal thing, and everyone casts and cleasnes slightly differently. Which is good, as it makes the ritual more personalised ansd suited to you.
It is also a good idea to meditate and ground yourself before the casting, as this centers you and focuses you on your task more.
You also dont have to mark your circle with chalk. My mum would kill me if I left chalk all over the carpet so I generally use ribbons or small nightlight candles of the appropraite colours to mark the boundary.
Also if your going to be doing a lot of things at once, e.g lighting candles, holding incense, walking the perimiter, its a good idea to memorise the chants and invokations, just so you dont have to carry around a sheet of paper aswell.