Check out these sites for themes and other decorating ideas.
Hostess with the Mostess – great website with lots of stylish themes organized by occasion.
The TomKat Studio – another great site with lots of bright, colorful themes, and tons of gorgeous pictures. A lot of pictured items are available for sale in their Etsy shop
Amazing Moms – this site is light on pictures, but has a long list of character themes and good ideas for accompanying activities.
When I plan a party, my first move is usually a Google Images search. Flickr is also a great place to find ideas, especially for cakes and cupcakes. A search on Etsy for party supplies will usually yield lots of cool decorations that you can buy or adapt to make yourself.
If you don’t want to be limited by a specific theme, try picking out just one or two colors and using those for tableware, balloons, or other decorations; Go with pastels or two shades of the same color for a soft, subtle effect, of pick two bright complementary colors for a more energetic vibe.
One popular trend I’ve been seeing a lot is to have bowls, vases, or large jars of candy in theme colors. Bulk jelly beans are usually easy to find in individual colors, or if you’re looking for something more unique, there are numerous online bulk candy suppliers, such as Candy Warehouse or Candy Direct.
The other decorating trends I’m currently in love with are round paper lanterns and tissue paper pom-poms. Paper lanterns are great because they come in lots of different colors and are easy to find, especially in the summertime. They can also be dressed up easily with a little glue and some paper cutouts to more closely match a theme. Tissue pom poms are also an easy way to dress up a party, and can be put directly on a table or hung above. Etsy is a good resource for buying pre-made ones. For the crafty-inclined, Martha Stewart has a great tutorial on how to make your own (she also sells kits).