Just reached lvl 80 as a hunter. What's next?

[soFLYafWOW]

I'm fairly new to WoW. I don't have even a tiny bit of knowledge about the game, a little bit of guide would help on what should I do next now that I've reached lvl 80.

My main is a Hunter (Horde) with a 1,613 gear score which I got from quests rewards.

[OhieMitzen]

Reputations quests for reputation and their quartermasters' items. Warsong Offensive, Kirin Tor, Wyrmest Temple, Argent Crusade and Knights of the Ebon Blade and Sons of Hodir.
Check AH for cheap BoE rares to boost your gearscore. I'd only recommend up to 200 ilvl rare quality BoE's.
Queue RDF while doing quests. Once you near 3K GS, start looking for Trial of Champion, Forge of Souls and Pit of Saron runs (Have to do quest in FoS before getting unlocking PoS), ToC runs may not require as much GS.
Then eventually you'll get to RDF HC as well as ToC, FoS PoS HC runs.