Rules for a good butter cream frosting:

First, make sure that you use butter. This may sound simple enough, but a little bit of butter won't cut it. You have got to have a stick or more. 

Whip the butter like there is no tomorrow on high speed. This creates a very light and easy spreadable whipped frosting. 

Try a new flavoring. I saw these great
flavorings from LorAnn Professional Kitchenonline awhile back, but never got myself to buy them. A week ago I ended up coming across them at Ross for a lot less. They have so many flavors such as red velvet, almond, coconut, butter vanilla, rum, lemon and a few others. I had to get coconut (because it's my favorite), and I also got the butter vanilla flavoring. These are flavor enhancers that you can put in cakes, frostings, sweet rolls, etc.  They are so good! Try them you will like them.