J.S.
Pipe the icing on using an icing decorator by starting in the middle and spiraling outward. It looks pretty and professional and you can get them done very quickly that way. Then just plop some colored sprinkles on them and voila.
I have the BEST buttercream recipe that's been passed down since my maternal grandmother... my memere.
Buttercream Icing
2 sticks unsalted butter (soft)
2-to-5 TB milk (or lactose free milk)
1 TB vanilla extract
2 lb bag of confectioners/icing sugar
1. Put the softened butter in a large mixing bowl and beat with an electric mixer it until it's creamy.
2. Add the sugar bit by bit until you've added half.
3. Add the vanilla and 2 TB of the milk.
4. Blend with the electric mixer.
5. Continue adding the sugar bit by bit, and if it becomes too stiff then add some more milk to soften it just so that it's pliable AND so that it doesn't burn out your mixer.
6. Keep adding until all of the sugar is in the bowl; you might not need all of the milk.
7. There should be enough icing for slathering onto the cake AND decorating it. Be sure to separate icing into different bowls in order to add food coloring.
By using this recipe, you'll have an icing that dries nicely and has a crisp on the outside but is creamy and delicious and far better than any canned or bought icing.
If you want an icing that won't dry, you can use half Crisco and half butter but the icing will stick to any wax paper or plastic wrap you use. I wouldn't use all Crisco and I would NOT use margarine at all.