Chalk

"Pen is mightier than the sword, but only chalk can f*ck sh*t up."

— every witch at some point, probably

Chalk has been used for centuries in ritual magic and in making basic portals and protection circles. Every single witch that is still breathing on this Earth will have some in their pocket. Those who haven't are not usually breathing anymore.
It does not really matter what colour your chalk is, although magic folk tend to dedicate certain colours to specific practices (for example white for exorcism and banishings, red for battle magic and blue for protection). What matters most is your intent and what words are you using. Chalks are powerful because they are a) easy to obtain b) easy to doodle with c) enhance the power of scripture no matter your practise and d) their dust gets absolutely everywhere, more than sand does, so it's extremely annoying for your demonic targets. Also it's a lot more practical to scribble something down with your chalk than to carry around a bucket of sand and try to whip out a mandala every time there's trouble.
Apart from being the "first aid" to any magical problem a witch might encounter, there are also some very powerful techniques in cretomancy and some mages have elevated it into true art. It does involve explosions but we do not recommend trying this at home, unless you don't mind not having a home anymore.

Quick Tips!

Do Not:

Stick the chalk in your mouth.

Do Instead:

Stick it in the demon's mouth.

Do Not:

Forget your chalk.

Do Instead:

Forget your artistic talent.

Do Not:

Draw a d*ck on the ground.

Do Instead:

Draw around the demon to send that d*ck back where it came from.

Do Not:

Try to draw circles, no one can draw a perfect circle freehand, TV shows are demon propaganda.

Do Instead:

Lines are just fine. Draw from your heart, let the hand guide you, just one line after the other. Demons hate borders. And if everything fails, just hit that abomination right between his eyes and run like hell is chasing you. Because it probably is, oh god - RUN!