also head over to agotcards.org. great community of folks over there and you can peek at all the cards before you decide which packs to buy.
An excellent suggestion to make sure you are coming up with the "better" options. It really is about quality, not quantity, in this game - particularly since "great" and "crap" pretty much cost the same here.
A word on "balance." You need to take it from a big-picture place in this game. I hear so many people talk about balance, meaning that they want every House to have the same options available to them, essentially thinking perfect game design is 6 different cards that do more or less the same thing. Personally, I disagree. I think the game would be considerably less interesting if every House "balanced" such that they could all do the same stuff. If every House was as good at Military challanges as Stark, or every House was as good at revenge tactics as Martell, or every House was as good at kneeling and buying stuff as Lannister, it wouldn't be an LCG. It'd be a board game where the choice is between being the top hat or the race car, not between being Targaryen and Baratheon.
The real balance in this game is that in the right hands, each House has a pretty equal chance of winning. Each House has its strategies, tactics, and personality, which a player can choose to match the way they like to play, but at the end of the day, there isn't really an "underdog" House such that no matter how good the player is, they are at a distinct disadvantage if they want to win.
What I'm trying to say is, look for the environment in this game to be balanced. Do not necessarily expect individual cards to be balanced, or for each House to have an easy answer to absolutely everything that comes up.