1) some type of dance degree that shows you dedication (minor or major).
2) some type of actual on stage or off broadway experience (maybe even as a choreogrpher or assistant).
3) some type of cross discipline knowledge (jazz, tap, ballet, pointe, lyrical/modern) is really great as it gives you personal dance diversity.
4) a positive, patient, energetic personality on the instructor's/studio's part.
You mention you want to teach dance/ballet class, no so much own or operate a studio. I personally believe that in either case you need some experience to teach with anytype of diversity and be able to group manage; basically, not be reteaching the way you were taught. Professional experiences will give you a "depth of field through actually have accomplished it" or "variety" of ways to teach through learning with other choreographers/instructors.
Hope it helps.
Keep smiling.[/i]