Hearthpwn

Look for Loot Hoarder, Injured Blademaster and Circle of Healing. Assume he can deal 3 damage on turn 2, so do not play Northshire Cleric or Zombie Chow on an empty board.

Druid barely play any minions with 3 health, so we can sacrifice Bloodmage Thalnos in the early game for the card draw. Also, the Piloted Shredder often lures out the Keeper of the Grove, so try and play it before Sylvanas Windrunner.

Out with the Zombie Chow and Loot Hoarder as early as possible. The probability that he's sitting on a Weapon is very high so make sure he's using them before playing Northshire Cleric. The Chow's are good for piercing his armor also, preventing an early Shield Slam. 

Patron or Control? Once you figured it out, save the Harrison Jones to ruin his potential whirlwind effect. If you don't have the combo Bloodmage Thalnos + Holy Nova while he's building up for a Patron attack, look for Shadow Word: Pain to kill his Warsong Commander

Our brethren Priest will probably be running a classical setup using some similar cards. Look for Nortshire Cleric, Loot Hoarder, Zombie Chow and Piloted Shredder. Since Priests are a bit slower in the buildup the Piloted Shredder can be really good. Shadow Word: Pain can be good to get rid of annoying Clerics with potential Velen buffs. Other than that it's pretty straightforward. So far I have 100% winrate against Priests, so there shouldn't be any problems.

Probably the class you'll be up against the most. In this matchup I look for either low cost drops, or the Auchenai Soulpriest + Circle of Healing combo. As long as it's Mech/Tempo Mage, just flood the board and always trade. We are in it for the long run and have the appropriate cards to withsthand a couple of bursts. When he's getting out of cards in hand, we can focus on the high-end cards to make the comeback.

Freeze Mage is one of the classes I'm having issues with at the moment...

Same instructions for all three. This deck is not perfect for aggro, so what we need to do is to try and dictate the tempo. Always mulligan for "soft taunts" such as Northshire Clerics, Loot Hoarder, and Injured Blademaster (even without circle). We need board presence at all cost while waiting for a board clearance. If you're having a lot of problems with aggro, consider subbing some of the high costs cards with Annoy-o-Trons.  

Look for how many cards he discards in the mulligan. All of them? Then it's probably a Handlock. In this case you need to look for Shadow Word: Death, Injured Blademaster, Piloted Shredder, and Sludge Belcher. All your 3 heal minions will probably die to a Darkbomb so you might want to keep on to them in the early game.

If you suspect it's a Zoo, check the instructions for Zoo.

A lot of the early drops will be good for Northshire Cleric as long as you go first. You can take of the divine shield and heal for a card on his Shielded Minibot and disable him from using his Hero Power as it would give you a card draw as well. Loot Hoarder and Power Word: Shield are also very good.

Harrison Jones and Sylvanas Windrunner are both very essential cards in this matchup.