Mulligans
Your main goal is to get Zul’jin out after playing Unleash the Beast multiple times and (preferably) Master’s Call, Dire Frenzy, and Animal Companion. This can take you from being completely out of the game to not only clearing a full board on your opponent’s side, but having a full board and a full hand on your side.
If you go against a Mage, you’ll want to be careful of Hero Skill kills on your 1 HP minions (except Shimmerfly, which should always open against Mage).
If you don’t get any minions, you might want to keep Master’s Call. It’s a great save if you get unlucky.
Keeping Scavenging Hyena is fine, but you should also have a decent number of minions with it for it to be effective.
Play Spirit of the Lynx ASAP if you have minions you can play after it.
Don’t be afraid to use Headhunter’s Hatchet early. It might get destroyed quickly, so you might as well use it.
–Class counters–
Always keep Unleash the Hounds against Druid or Warlock. And don’t you dare play it unless you’re overrun. That’s what they’re in there for.
Tracking works great against Bomb Warrior, but I’ve found 2 to be a bit excessive.
Try to bait Mage into using big AOE spells on your grunts before you pop off cards like King Krush and Unleash the Beast. If they wait, punish your opponent by using Dire Frenzy on Springpaw, Shimmerfly, Hench-Clan Hogsteed, Scavenging Hyena, or Animal Companion.