Don't just think out of your head.
A cake design may be pretty in your head, but sometimes the interpretation can come out differently on the actual cake. My hubby (he is AWESOME by the way) gave me the idea to draw a cake before you make it.
Quoted from him: "Cake decorating is an art."
How true is that??
Being the good hubby he is, he went out and bought me a drawing pad and some nice colored pencils to help me on my way!