And just to add my 2 cents i have always played Marksman iv tried the other 2 specs but just couldn't get into them. Beastmastery is only "fun" because you can tame some pretty unique pets only available to that tree but other then that its still to my knowledge the lowest of the dps specs. Don't get me wrong for lvling and beginning dungeons its not really all that big of a deal but if you want to be the best you can be marks or survival are the way to go for end game. Of course if you find you like playing BM over the other specs then go with what you enjoy though with duelspec available its easy to have your secondary as one of the "better" specs for raiding if thats the route your eventually going to go.
As stated
http://www.noxxic.com/ia good place to look and very easy to navigate. I personally don't like elietest jerks as you have to wade though posts to find anything useful.
the other thing you should think about doing is getting professions since a few of them can give boosts to your character, Enchanting for ring enchants, inscription for a good shoulder enchant, Leather working for bracer buff, Jewel crafting get you 3 uber gems for slots, blacksmithing for a couple extra sockets. Just as a warning you can only take 2 prime professions and would suggest unless your planning on farming dailys to make a ton of gold to pick your other profession to pick mining, skinning or herbalism to match your other profession(with the exception being enchanting as it can stand by itself).
