My neice was married in Las Vegas and wanted me to do her cake with the theme of Las Vegas. Now I am not a professional but I do make these for my close friends and family. Because they can forgive the mistakes.
1for the cake just make off the directions for you cake mix
mix powderdsugar, butter, shortening, and vanillia untill fluffy. Add milk slowly until you get the right consistency. You may need to add a little more milk.
3the trick to icing is you put a crumb coat of icing on the cake the night before you want to finish the cake and store in the refridgerater(crumb coat is a light coat of icing) The next day ice the cake by layers.Stack the layers and then decorate to your hearts content. But remember less is better.