Children and teenagers often like brand-name characters on birthday cards - not just Disney (though I think Frozen and Avengers birthday cards are very popular!) but other things like Forever Friends and the Me to You teddies. When I was younger, Purple Ronnie cards were all the rage, along with a family of hedgehogs that I can't remember the name of.
I bought a pack of die-cut stickers showing Bang on the Door characters ages ago and wasn't particularly inspired with what to do with them, as they are pretty vibrant on their own. So I used them simply on a white card, with some silver heart and star die cuts from the same pack around them. The 'special birthday' is from a pack of outline stickers I've also had for a long time. Not my favourite card but it might go down well with a pre-teen girl!