First, make them mini. Anything little is automatically more feminine. Use adorable paper liners that could easily be mistaken for the finest of stationary. As for the recipe? Funfetti... obviously. But be sure to use Rainbow Chip frosting. You can't beat Rainbow Chip frosting... unless you add pink food coloring (of course.)
While the cupcakes are in the oven, do facials and manicures. After the cupcakes have cooled, and your nails have dried, blast Taylor Swift songs and sing along as you give each one a haphazard swirl of frosting on top. The smudgier the better. Finish with bright, sparkly sprinkles and edible glitter.
Note: a sister isn't required, but she makes everything more fun.