But Reddit user pulandit has posted an incredibly helpful guide to picking cards in Hearthstone's arena. He's created a chart of every card in the game, grouped by neutrals, and then the ones specific to each hero, using a font classification to rank them from the most useful to the least.
If you take a glance at the image to the right, which I've pulled from his guide, you can see that the Azure Drake is a great choice, the Argent Commander less so, the Archmage is fair, while the Arcane Golem and Argent Squire are considered below par or situational, and the Angry Chicken is not recommended.
While you may not agree with everything in the guide, it's not for advanced players, but for struggling noobs like me. But even so, check it out, you might just learn something!