As a new player decide to concentrate on either Pariah of Iron, or Bone. Pick up the key models for that. Except for Ashes and Dust. Just get him.
For Iron get 2 of the following: Mechanical Rider, Teddy, Lazarus (just a good buy period, can always be used) or Ryle
For Bone get 2 of the following: Yin the Penangalan, Izamu the Armor, Madame Sybelle. Then get Rotten Belles no matter what you picked.
That is what I would tell a new Levi player. Obviously there is a ton of options to go from there.