Cut a piece of wax paper the same size as your cake. Write directly on the paper instead of the cake and freeze it. Gently peel the frozen letters and words off the paper and place them on the cake. (smarty pants!)
Holy smokes. This may be the best crafting tip of the month. "print out the font you want and place wax paper over it. Trace letters with puffy paint, let dry, then use mod podge to secure letters to canvas, etc. Brilliant.".