The decorations will actually depend on which princess theme your party is based. For example if you choose an Alice in Wonderland theme, make a small cardboard entrance to your house, decorate the party room with mismatched tea cups and saucers, small chairs and table etc. However, if you are not keeping any theme, you can simply decorate the party hall with lots of pink stuff like confetti, balloons, streamers etc. To give a royal look to the party hall, decorate the tables with fake fish bowl centerpieces surrounded with fake pearls. You could also keep a small treasure chest at one corner of the room or even display the precious fake pearls and glitter stones on small stands throughout the room. The princess can take the guests on a round showing off her wealth! Also decorate the staircases with fresh flower bouquets, and silk drapes. The dress of the princess is also very important, the dress of the little princess should be grand, something like a pink satin gown. Also make or buy a tiara for the host, you can make the party more exciting by making the princess enter only after all the guests have arrived! Read more on princess party idea.