Nothing makes party planning for kids easier than using the trusted themes that have proven themselves over and over which are.
Make the party an outing.
Getting out to a place where the guests can be active is a great alternative to having the party at your home. You can make it a day at the zoo, an amusement park or a picnic at a lake. The great advantage of having a party this way is that you won't have to clean or decorate the house. You always want to ask your little one what she likes before going ahead with any of the following themes. Other parents can be a big help if you have a lot of kids coming to the party.
The little princess.
Most girls love the thought of being a princess. Because of this, princess parties are usually a great choice. Most of the time, you'll want to have a guest list made up of all girls. However if you want to have boys come, each one can dress up as a prince. Making sure your guests have the right princess dresses and costumes can add a lot of fun to the party. Hire a princess to come to the party and tell her princess stories. The girls can learn a princess dance and wave.
Have a pony party.
Almost universally, girls love ponies. Ponies can actually be brought to your party or you can sometimes find places who have them locally. These are perhaps the most fun because they get to actually ride real ponies.
A luau party is a great idea - especially if it's warm outside.
Get your birthday girl a grass skirt to wear over her swimsuit. Have some for the guests and their parents. Using tropical and beach games can add some authenticity. Inflatable pools and water toys can be a great substitute if you don't have access to a pool.
Focus on fashion.
If your little girl is into clothes consider theming your party around fashion and great outfits. Add a runway and some in vogue elements like sunglass and flash bulbs and you are well on your way. You can do this with a low cost approach as well. Making your own fashions or getting them from thrift stores help saves cost. Think about having a photographer there taking fashion and catwalk style photographs of the girls in their best fashion poses.