For my little sister's birthday cake, I was going to do like a pair of high heels and a tube of lipstick on a cake covered with hot pink icing?
It sounds adorable...as long as she's a teenager or older
Um, didn't you say your little sister is turning two? (Or is there more than one little sister?
If she likes shoes -- which a lot of toddlers do! -- go with something a little more age-appropriate, like a pair of sweet mary janes, maybe with flowers or a butterfly or something on the toes.
Or maybe a FBCT pic of a little girl playing dress-up, wearing much-too-large pumps and holding mom's lipstick.
But high heels and a tube of lipstick, as cake decorations by themselves, are better suited for a girl who's at least middle school age IMO.