What age group is this costume for?
Preschool and Younger
Elementary School

Estimated time required to make this costume:
About one hour- As little or as long as you want!

Difficulty level:
Quick and easy - no sewing required

Items you will need: (Hit your return key to start a new line)
Purchased witch costume with hat
Glitter Glue
Sequins
Googley eyes
Jingle Bells
Whatever strikes your fancy!

Instructions:
Purchase (or make, if you so desire) a simple witch costume. I found that witch costumes are very cheap and easy to come by. If you have difficulty finding one in your child's size, a larger one can be modified by trimming it to size. No need to hem- cut an exagerated zig-zag pattern instead.
Prepare your work surface by covering with a vinyl tablecloth or newspaper- if this project goes well, it will get messy!
Decorate however you wish!

Other information to consider:
With this costume, half the fun is in the making! Give your child free reign, and join in on the fun, but let it be the child's design. My daughter delighted in showing off the costume that SHE made!
If your child has long enough hair, try braiding her hair several hours before, then undoing the braids. Turn head upside down and spray liberally with hairspray, preferably aersol. This makes hair look really witchy! (Also a good technique to make a girl's hair look like "Hermione" from "Harry Potter")
To look extra fancy, try glitter hair gel or spray, and glitter make-up.