Not everyone is able to begin an expansion... well, at the beginning. Lucky for you (and me) Blizzard realizes this and has made it a little less daunting to try and get into the second raiding tier without doing all or any of the first. I'm torn on this particular design strategy, for players like you and I, getting into content late, it's a blessing. We don't have to feel that we're behind, or holding our friends and guild mates back. On the other is does trivialize the content to some extent. But that's all I'll say on the subject for now. This article is about getting your hunter(or other class) raid ready.
If you are just beginning your Cataclysm Raiding adventure your gear may not be the greatest. Hopefully up to this point you've been doing 5-man dungeons and possibly heroics. If not, this is the best place to start.
The three ilevel goals you have to hit to run dungeons are 226, 272 and 305. If you're leveling by questing 226 and even 272 will probably be pretty easy for you to hit. 305 may be a bit of a struggle, however. But never fear, justice points are here! You will receive 140 justice points for the first seven dungeons you complete using the dungeon finder. You will also receive points for killing each boss. With those justice points you can buy shiney new gear. As of 4.2 the gear that was previously purchased with valor points are now purchased with justice points. Rejoice!
Once you are at 305 and can run every Cataclysm dungeon on normal mode your next goal is 329. An ilevel of 329 gets you in to every Cataclysm Heroic mode dungeon, except the Zul'Aman and Zul'Gurub instances, which have a separate queue. You will still get some justice points for this, but you will also be recieving...
Valor points are like justice points... only better. You receive seventy valor points for each heroic dungeon you complete using the dungeon finder; again you can receive this reward up to seven times per week. You also receive 140 valor points up to seven times a week for running the Rise of the Zandalari Heroics, Zul'Aman and Zul'Gurub. You will need an ilevel of 346 to visit these dungeons, but the gear you'll receive for your efforts is much better.
Around the time you're ready to begin ZA and ZG you can also begin looking for Baradin Hold groups.Baradin Hold is a 10 ro 25 man raid dungeon with few trash mobs and two bosses, one new as of 4.2.
Baradin Hold, Zul'Gurub and Zul'Aman
You'll likely find most of the gear you'll need to begin raiding in ZG and ZA and you can get a few tier 11 pieces from Baradin Hold. Again, you will need an ilevel of 346 to visit these ZA and ZG, and a lot of group are going to want you to be near here to visit BH as well, though your ilevel can be slightly lower. I recommend you pick up every quest, as one of the quests in ZA provides a tanking bow you may want to use temporarily. I know the stats will hurt your hunter soul, but you'll want to look at the damage, this is the number one most important thing for a hunter. There's also a bow that drops from Jin'do the Godbreaker, the last boss in ZG. You'll also find an uncommonly good looking cloak, but sadly it's not as good as the one you'll get from...
The Call of the World-Shaman
I really, really, really enjoyed this quest. It was fun to do and gave me a very nice cloak to wear around. Lookin' good!
Previous Tier and Firelands Trash farming
Finally, if you've done all of the above your ilevel is hopefully in the 350s. From here you can begin going to the previous tier of content and some Firelands trash farming. Blizzard has stated that they would like the previous tier of raid content, Black Wing Decent and Bastion of Twilight, to be pug-able. To make this a little easier for everyone they have made all of the normal modes of these dungeons easier with lowered boss health and damage output.
It takes some sitting around in trade, but there are some Fireland's trash farming groups out there. Just make sure you are aware of the rules for receiving these BOE items, especially in a group partly comprised of players from the same guild. I've seen a lot of "Guild X ninjas!" reports in trade that boil down to a misunderstanding of the expectations of who should receive an item.
That should get you through! I'd like to note that you do not necessarily have to do all of these, you can also get items from questing and crafting, and you may find that you don't in fact need to visit the previous tier of content or do Firelands' trash runs to be well received in a Firelands raid. However, if you are coming up a bit short, I hope the above will help.