Plan on a mess so be ready... If you have a small table that can be set up as a temporary work station for the kids that is just at the height for them to stand and work, that is great.
I use a small 30" x 30" table and then cover it with a Christmas plastic flannel back tablecloth from the $ store... it adds to the festivity and makes for easier clean-up!
The floor can get pretty sticky sometimes... if you're concerned buy a cloth paint "drop cloth"... I would advise you to wash it a couple of times and even throw in some bleach as they are a bit stiff when they are new. Spread the drop cloth on the floor and tape it down with blue painter's tape (it won't damage the floor)... and then you pick it up and shake it out and throw it in the washer!
A really fun thing to do is to have the kids actually paint on the drop cloth and personalize it!
Keep the waxed paper handy during your creating... it's magical stuff!
'Tis the season to get cooking with kids! Merry, Merry!
Happy Holiday Cooking with Kids,Jan McCracken, Culinary Coach