Wine - Portable wine/butterbeer chalice so I don't spill a single drop of deliciousness while walking around Hogsmeade/Hogwarts. Every witch and wizard needs a portable, spill proof goblet.)
Broom - "Magic" wall organizer Cause where else is a magical broad supposed to keep her favorite mode of transportation? A broom barn? Pfffft. Not bloody likely!
Hat - Sunhat. There's not too much shade in the quidditch stands and even non-muggles don't want wrinkles/skin cancer, ya dig?
Book - [Skeleton Crew] (http://www.amazon.com/dp/0808571524/ref=wl_it_dp_o_pC_S_ttl?_encoding=UTF8&amp;colid=1MGNSTGZPRBLJ&amp;coliid=I14E0NXLLQCDW9)Essential in learning about the supernatural/paranormal. The best defense against the dark arts is to know thy enemy.
Trunk - Elephants got 'em too. And this little necklace/earrings are the cutest and most portable way to show off your trunk. Cause no one wants to lug around an actual trunk all the time! Can you even imagine trying to get a trunk up and down the disappearing stairs between classes? NOPE.
Cloak/Cape - Velvet or Invisible, either one will do. Every good witch deserves a cloak.

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Reddit mentions of Skeleton Crew (Turtleback School & Library Binding Edition)