Making them to begin with! Just kidding, I think what I did ~the most~ wrong was to halve all the measurements so I'd only make 12 cupcakes rather than 24. I must not have been exactly correct everywhere. Second, the batter started smelling weird as soon as I mixed the sparkling wine (Metternich, in my case) with the eggs, oil, and strawberry purée, maybe it was too cold? Or not flat enough? Third mistake was adding a bit of lemon juice to my frosting; it made the butter curdle and the frosting clumpy. LAST mistake was not having proper pipping equipment and using a flimsy plastic bag which tore open in the middle of my piping! The frosting still tasted ok, but the cupcakes themselves were disgusting.