Druid:

The main strategy here is to buff a Stoneskin Gargoyle and let the AI suicide everything into it while you just go face. If you get Echoing Ooze+Mark of the Wild early, that can also be an alternative way to get a fast game. Usually the ideal game is one where you only have one creature which is a Stoneskin Gargoyle that gets buffed to something like 5/8. This just makes the game extremely fast because you only attack with that one Gargoyle and he will just end up running everything into it. It's important to avoid having damaged minions on the enemy board because he will often use Battle Rage which takes really long.

Mulligan: You should always keep Mark of the Wild and Innervate. If you already have a Mark of the Wild or Innervate + Mark of Nature I would also keep a Stoneskin Gargoyle, but if you don't have that, you should discard the Gargoyle since there are 5 in the deck and you will usually draw one soon enough anyway. Echoing Ooze should be discarded unless you already have a Mark of the Wild and no Gargoyle.

Rogue:

In this match you should almost play like you would against a normal player but with a bit more risk. In most cases you want to take favorable trades instead of going face. Make sure to force him into bad trades with your taunts and attack his minions with your hero when it makes sense. There isn't really any opening that always gives you a fast game here because it depends a lot on his cards. I would just go high risk and play your 1 mana minions on turn 1 if you have them. If he has a Webspinner or coins a Haunted Creeper it's kinda bad, but since it's just the second game I would just go for the high risk play and play the 1-drop since it's important to have as many minions as possible on the board. If you get Tinkmaster and you don't have another good play or you are in a bad situation anyway, I would just use it and hope for the best. It's also perfectly fine to use your Mind Control Tech or SI:7 Agent as just a 3/3.

Generally you will have long games here pretty often but since it's early in the run, it's not a huge deal.

Mulligan: I would keep every 1 or 2 drop and keep SI:7 Agent. If you don't have SI:7, keeping a Mind Control Tech is fine too.

Hunter:

In this match the opening is pretty important to make sure that you don't die. If he starts with a Deathcharger, don't run your first Webspinner into it because you will need all 3 of them on turn 3 to be prepared for a possible Flesheating Goul. If he plays anything else on turn 3, just kill the Deathcharger with the Webspinners. From then on it's hard to have a general strategy since your minions are random but it's just important to not go all in too much, since he often has Poison Seeds. He will often use his 5-damage spell in a stupid way and also uses the 1-damage AoE on 2 minions sometimes, so you shouldn't go all-in too much and kinda just wait for him to spawn some spores. Sometimes you just get unlucky and lose without anything you can do, but if you learn how his AI works that happens much less.

Mage:

There really isn't much to explain here, since it mostly plays like a normal game with him having a crazy hero power. Don't play Undertaker or Secretkeeper on turn 1 or 2 and don't worry if you just play nothing until turn 3. Later you just want to fill the board with big minions and go face unless you get an amazing trade. Playing Duplicate and Mirror Entity is awesome, Spellbender, Counterspell and Vaporize can be pretty good too, but I would only play them for free or if you really don't have another decent play.

Mulligan: Always keep Nerubian Egg, Mad Scientist, Kirin Tor Mage, Duplicate and Mirror Entity. If you don't have another 2-drop, you can also keep Loot Hoarder and Bloodmage Thalnos.

Shaman:

This is a pretty simple match in general and the time usually doesn't vary that much. You shouldn't worry too much about getting too many Souls. The animation is slow and annoying but often you jsut can't really avoid getting them, so I wouldn't go out your way too much. If you get an Earth Elemental, use it as early as possible and heal it with Reincarnate if you can. When that doesn't happen, you will just have to play your other big minions and win it a bit slower.

Mulligan: Always Keep Haunted Creeper, Flame Tongue Totem and one Earth Elemental. If you have a cheap activator I would also keep Nerubian Egg.

Warlock:

It's helps a lot to get an Unstable Ghould, Void Walker or Imp Master early because he can easily kill you if you can't do anything until turn 4. I would not play a Felguard on turn 3 unless you don't have a Voidcaller. Ideally you want to have as many Voidcallers on turn 4 so that they just spawn the next one when they die. You should generally only use your removal spells when you can't play a minions or when you can kill all his minions on that turn. If he has a secret, I wouldn't kill a minions unless you can't really avoid it. Generally it's usually better to first get all of them low, because the early avenge damage can be very crucial.

Mulligan: Keep Unstable Ghould, Void Walker and Imp Master no matter what. I would also keep 1 Voidcaller every time and keep 2 if you already have Unstable Ghould, Void Walker or Imp Master.

To be continued...