You can read here about one of my daughter's Halloween costumes. The other one wanted to be a (friendly) ghost. I ordered an inexpensive white tutu from Amazon. Then I picked up a white long sleeve shirt from Target, and some black felt from the craft store.
I found a free ghost face printable online. I printed it and cut out the pieces. I pinned them to the felt and cut them out.
Then I pinned the felt to the shirt. I had my daughter try on the shirt to make sure the placement was where I wanted it. Then I just hand stitched the face onto the shirt. It didn't take long at all!
Final product! So cute! She wore it all October long.