She's so cute!
You can use anything really, usually for Story Ornaments you use the regular colored glass ones or plastic (glass is better though). They can either be round or flat, doesn't matter to me. For the paw print, I would leave that one be to tell it's own story, I mean I could paint on the back if you wanted me to, that's up to you but I think a different ornament would be nice too ^_^
RJ (H. Lifalili), Acara (EB)
Ghost, Trip (Angels)
Leopards: 2:3 Hawkeye, Cullen, Luna, Astrael, Dorian