Commander gear is the best, but not an option since you're just starting. (Also note, veteran gear is not very good and costs a lot of tickets, I suggest you skip it)
Winter Palace set from the Yuletide Packs gives the next best stats. If you don't have the Level 10 tier set already, or don't have the money to go pack-diving this holiday season, then this won't be an option either.
Be aware that free gear is at a disadvantage in the arena. To compensate for poor resistance, make sure your pet has Spell Proof and Spell Defy trained. I suggest you try the Gloomchill, Sorrowscale, or Dawngrave gearsets (craftable, recipes from Zamfir) or else use Suten's Hood of Repose, Balmy Tunic, and Keymaster's Languid Boots.
If you can spare any money for a Heartsteel athame, buy it. It's the best crowns investment a low level PvP wizard can make. Ring and deck, up to you.