Yes,personally I do cast a magic circle everytime I perform a spell but of course that's just me.I would advise you to cast a circle too for a hoodoo spell.There are plenty of reasons for casting a circle(creating a sacred space,containing energy,keeping unwanted energy out).Furthermore,it is believed that the circle is 'between the worlds', that is,
between this world and the next, the dominions of the gods.
It is most convenient to mark the circle
with chalk, paint or otherwise, to show where it is; but marks on the carpet may be utilised. Furniture
may be placed to indicate the bounds. The only circle that matters is the one drawn before every
ceremony with either a duly consecrated Magic Sword or a Knife.
Athame or Black-Hiked Knife, with magic signs on the hilt, and this is most generally used. When drawn, this circle
is carefully purified, as also are all who celebrate the rites.
It Is necessary to distinguish this clearly from the work of the magician or sorcerer, who draws a
circle on the ground and fortifies it with mighty words of power and summons (or attempts to
summon) spirits and demons to do his bidding, the circle being to prevent them from doing him harm,
and he dare not leave it.
The Witches' Circle, on the other hand, is to keep in the power which they believe they can raise from
their own bodies and to prevent it from being dissipated before they can mould it to their own will.
They can and do step in and out if they wish to, but this involves some loss of power, so they avoid
doing so as much as possible.
Furthermore,I'd highly recommend you to check this site out http://www.meddevi.com/witchery/circle.html
and also this video: http://www.spellsofmagic.com/videos.html?cat=casting&v=4L1kiY_GvK4