Hi K.! Princess parties are so fun to plan! Last year we did that for my daughter's fourth and i combed the internet for ideas and was really pleased with the way it turned out! I made the invitations, which got plenty of kudos from kids as well as parents...they were printed on a colored fiber paper which I then used rubber cement to adhere to a half sheet of plain printer paper and rolled and sealed with a gold label and tie addressing each child as "princess-" or "sir-". They were written to sound "royal" and invited guests to dress in their favorite "royal" attire. My daughter dressed as sleeping beauty, her godmother agreed to dress up like cinderella, I dressed like Belle, and another friend dolled herself up like a princess as well.
Of course we had your typical decorations: balloons, table covers in different colors, princess banner, etc. I ordered goodies from oriental trading co.(plastic princess cups and knight cups and sword bubbles, stickers, tattoos, etc) as well as gathered things from the dollar store and party stores (bracelets, candy, etc.). Each goodie bag was labeled with gold label "princess-" or "sir-". I made a big frog prince with a gold glitter crown and cut out lips for each child to play "kiss the frog prince". We also had a craft table to make crowns/tiaras (found a kit at ac moore i think??? and a bucket of glitter pens). We had intentions of playing princess tea party and birthday party music cd's but the radio we used wasn't quite loud enough and gave us some problems. My special gift to my daughter was a rather large princess playhut (ordered from walmart online) which we set up connected to her brother's MegaPlace Playhut tunnels and tents so the kids had a little obstacle course/entertainment area.
Another thing you can do to add a special touch is print labels with a little design on them and the birthday girl's name and date or something. The labels fit perfectly on Hershey's Nuggets and then you can just scatter them around on tables. (I found pics of disney princesses online and did 3 different labels each saying something like "thank you for coming to Princess Anastasia's royal ball" or "Princess Gracie's Royal 4th Birthday and the date". As for food, we set up a buffet of all sorts of easy stuff for kids to include a big bowl of grapes and strawberries, a treasure bowl (dirt dessert with gummy jewels), cheeses and crackers, hot dogs, sloppy joe, etc.
Anyway, I know this is a long response...I just thought I'd pass on some fun ideas. Hope you find some useful and enjoy planning your daughter's party! Btw- I do custom cake decorating. If you'd like some info feel free to contact me....I noticed you are in Nepa.