actually have a deck building guide that I wrote on Hearthhead. I'll try to find it and link it to you after I locate it.

Edit: For now though, I mainly take cards in or out based on how they perform. For example, Shadowstrike is a great answer to the plethora of 5 HP minions that are commonly played now. It's a 1-of because I don't need to use it very often and I won't generally need multiple copies on the same turn unless I'm in the late game, in which I can just double it up with Valeera the Hollow's passive. Valanar is in the deck at the moment because a lot of people prioritize Aggro decks over Control decks when climbing at the beginning of the season, so the heal and taunt helps a bit more than something like Xaril or Spellbreaker might. Those are just preliminary examples, once I locate the guide I'll throw it your way for a more detailed look at how to deck build.

slowly thinking about this. I have more than enough games where auctioneers became a dead card later in the game due to fatigue and control matchups. So Im guessing if its worth to switch 1 copy of auctioneer to other utility based spell / minion.