Sorry Liz, just saw your post now!

In that situation i would say "DD we draw on PAPER" and give her paper. If she drew on the wall again i'd say "do you want to draw on paper or do you want to put the crayons away for now?" If she did it again i'd take her crayons away - i actually make HER put them in the tub and then i put the tub out of reach.

Bx