A cupcake tip from my friend Melissa at 320 Sycamore:

This Wilton cupcake set is perfect for making boring cupcakes look cute.  Use the 1M tip and fill the disposable bag (that come with the kit) with your own frosting or store bought and just swirl that frosting on. It does take more frosting to decorate this way-buy two cans of store bought, or make a big batch of homemade.

Here's a great frosting recipe:
1/2 cup margarine
1/2 cup shortening
1/8 tsp salt
1 1/2 tsp vanilla
5 cups confectioners' sugar
1/4 cup milk
In a large bowl cream margarine and shortening until light and fluffy.  Add salt, vanilla  and sugar and milk and beat well.