Cake!

So I made a little cake last night with my left over cupcake batter. I need to practice getting the icing smooth...who knows maybe soon you will be ordering a Posh Cake instead of cupcakes! I can do cakes if they are covered in fondant I'm just not good at making icing smooth or crumb free for cakes with just icing....I'm going to keep practicing though! Ill post a pic tomorrow of it.  Any tips on how to ice a cake??