For my daughter's 3rd birthday, we had a Cinderella party.
We used pre-printed Cinderella invitations that matched the paper goods we bought. We rented a bouncer for the backyard that looked like a big castle and the kids loved it. The bouncer was much cheaper than we thought and the company had a great "rain policy" if the weather was bad on the day of the party - check out the bouncers because you might be surprised. We played "Pin the Glass Slipper On Cinderella" and each child received a prize for trying - we used Princess fruit rolls for prizes. The cake was a doll cake decorated to look like a princess - Wilton makes the doll cake pan. I also made cupcakes to have extra cake for everyone and decorated the cupcakes and cake with edible clear sprinkles so it all sparkled. The table was a long child size table borrowed from preschool so it looked like a banquet table. The children each took home a Cinderella coloring book, tiara/crown, glitter crayons and cookies. This party theme would probably work better for an older child and for an all girl party, but my 3 year old is obsessed with Disney Princesses so she loved it. The tiaras for the girls were a big hit, too!