As i see it, there are about two ways to plays each hero, here they are :
Jaina is good with spells. With her, you shouldn't play a lot of creatures. You can either play a lot of harmful spells and creatures, a lot of control spells (freeze, mirror image), or a mix of both. With that type of decks, you should play creature that does effects when you play spell like the questing adventurer, the mana wyrm, the auctioneer, .. For more control options, add frost or water elementals.
Malfurion can be played either really aggressive or control. You can play with feral spells and a lot of low to mid-range creatures, using the hero power to deal and tank damage. Or you can play with your mana curve with spells like innervate and wild growth and focus on playing big creatures for a lot of mana quickly. For the control version, you'll want to add healing cards to help you survive through the first turns.
Uther is a hero that prefers a lot of creatures. For that hero, you want divine shield creatures for a low cost and some more beefy creatures. Get some spells for inflicting few damages and get creatures, spells to improve them and make them survive each round The more you'll have creatures on the board, the better you'll feel. You can also play a deck with more direct damage and fewer creatures that have effects based on other creatures, like the flesheating ghoul and the cult master.
The two main abilities of Valeera are stealth or combo. Play stealth creatures for an aggressive strategy and combo for a control deck. Combo cards work together so you'll want to keep your cards and play them wisely together. Play low cost creatures and spell that deal damage, put two headcracks in that deck and don't forget to use your hero power. Or you can play with stealth and battlecries. .
Anduin either deals or heals damage.You can use cards like mind blast and auchenai soulpriest if you want to kill your opponent with direct damage from healing spells. You will want creatures with healing and damaging effects and mix those cards to survive and kill your opponent. With the healing version, get creatures with taunt and massive health then get spells that double health, creatures with passive buffs when healing and build huge tanks. You can add a mind control spell or two to be ready for any situation.
Rexxar is a hunter and hunters like beasts.Play a lot of beasts together. Everything that gives a buff to another beast is a good card. Get direct damage spells for aggression and secret spells for more control options. With this hero, you want to make damage fast and finish your opponent with the hero power or the shear amount of your beasts, or even a charge attack with the kodo beast.
Thrall has a gameplay based on its totems. It's two main abilities are overload and windfury. You can associates creatures and spells that have these abilities and mix them together with totems and buffs to deal massive amount of damage in a single turn. You can also benefit from the fact that you have one free creature each turn to play a frostworld warlord, a raid leader or a stormwind champion and turn your deck into a minion orgy.
Gul'dan is aggression. You can play the demon deck, creatures are a bit costy, it's a mid game aggression deck, you start to clean the table and then put your big fat minions. You will want to keep the discarding cards for when you have no other card in your hard, you'll use them in extreme emergency only otherwise. Pr you can play a murloc deck for an extremely fast deck. Use your hero power to draw cards and keep that aggression. If you want to put control spells in that deck, you'll play all your murlocs the same turn, keep them alive and buff them with the murloc warleader or the coldlight seer and you'll have a massive army prepared for the next turn.
Garrosh has a wonderful hero power, build an armor and tank the damage. Destroy minions with your warrior spells combined and survive to play all your warrior creatures. You can play one minions each turn if it can survive for the next one or impact the board directly, creatures with enrage are good here too. You can also play more direct damage spells and minions with charge to overwhelm your opponent quickly.
Random tips :
- Minions with one health are bad alone, you must think of playing it with another spell or creature. On the other hand, minions with 2 healths or more are better.
- Active buffs are great.
- Each card you play must have an impact on the board. Otherwise it's not a good enough card.
- Silence is a freaking great ability for both mode. Now, it also removes buff, making it even better.
- Like every card game, the more you wait to play your cards, the better it gets in most situations.
- Weapons are assured damage, keep the durability for the best occasions.