Goods usernames for Tumblr would be one that you like.
Good usernames for Tumblr should be unique and creative. Make a username that is an expression of who you are and your personality.
I put a link to a list of Pottermore Usernames in the related links. There are some good ones.
Good usernames all describe the person YOU are so if your girl here are some awesome usernamesYellowbellBabyCakeFlowerFairyDramaQueenBackstabberBluffingwithmymuffinLadyGoogooPok8rfaceMuffingCrystalStalkerStrawberryGlossCrazyBabyKandyDynamiteYou can also use you're fav song
Good usernames for dancers should convey how much they love to move their body. Some examples are joyfuleaper, gracefulone, fluidlimbs, movingart or dancingdamsel.
It isn't scary but maybe you would like KittensForBreakfast.