We checked out a cute book from the library called Halloween Hats. In rhyming text the book describes all the types of hats you might see on Halloween. The neighborhood kids (with their hats, of course) gather at the same party where they play a fun game that involves switching hats and celebrating their now mixed-up costumes.
Obviously, we needed to make some of our own Halloween hats. I used colored party plates we had left over, but you could paint some regular paper plates. We made a princess and a monster (or bug or alien. I don't know what it is really) but the possibilities are endless. Just cut the shape you want to stand up from the middle of the plate.
Then bend the pieces up.
I added some google eyes to the monster hat.
And some red glitter stars to the princess crown.
We practiced trick or treating with our hats, mostly the "trick or treat!" part and the thank you part. (And they insisted on the getting the treat part.) If your kids are ready for more, there's a great post about trick or treat etiquette at JDaniel4's Mom.