Here’s a recent example of a cereal box birthday invitation for a 2 year old. For this one I tried using the at-a-glance icons at the top of the box to give the important facts (time, date, place).

Before ImageCereal Box Birthday Invitation

Most of the work on the original picture was to extract it from the background.
On top of that, I mainly lightened up most of it, and then did some dodge & burn painting. I also painted much of the glow in the background to make it more irregular-shaped, and not just an even glow all around her body.
You can see a larger version of the final result here: Nouncement Gallery.