Best sources for Hearthstone strategy guides?

Well, im platinum 2 stars in both ladders, and unfortunately there arent that many strategy's for now, you just need to play around to see the most common decks, for example ranger plays beast, either blitz(one attack win) or mid-game own...
I really enjoy making decks, thats all.

ps. for Arena plays/tips totalbiscuit@youtube might help you a bit

If you watch any videos, watch Trump's stream or his past broadcasts, especially during his Arena drafts, which are arguably on of the most important parts of the game

Since "Mana" isn't a "problem" like in Magic, decks revolve around the "curve".
Haven't played it my self, but if you make a deck with a great mana curve and some good cratures youare set to go blasting.

Honestly its easy enough to get into by yourself and whatever advanced stuff/theorycrafting you would learn now is going to be useless after the next patch :p
For general info http://www.hearthpwn.com/ is pretty nice you can read players comments on the specific card/spell

Also check out Ribbo's Arena Runs. He usually gets 7 to 9 wins in Arena per hour and a half-ish video. I learned a lot while watching his arena runs.