2. Battlefield Barrens gear
If you want to take advantage of this, you're going to have to act fast. As WoW Insider posted, Battlefield Barrens content is disappearing come patch 5.4. It is unclear, as of yet, whether the lead-in quest that awards the ilvl 502 boots will remain, but it seems very unlikely that it will. So get that quest and get it done, pronto. Don't hang around, it'll be gone before you know it! It's not hard at all, simply speak with Cho in the Seat of Knowledge, do a couple of scenarios, then run through the quests of either dealing with Senjin Village or being a cat, depending on faction, and you're there.
With the Timeless Isle offering ilvl 496 gear, obtained far more easily than the Battlefield Barrens, it doesn't seem like a high priority to complete the weekly quest. Effectively, for the Battlefield Barrens, get the boots, then get out of there.
3. Shado-Pan Assault
While we'll get to valor in the new patch a bit further down the page, it's worth mentioning these guys -- they have a 522 neck available at the reputation you'll have when you first meet them. With a bit of caution regarding the information below on valor in patch 5.4, it could well be worth buying that neck for an item level boost.
4. The Treasure Room
With the above, we're looking at fairly controllable items. You will know what you can buy with honor gear, and the boots from the above quest are pretty set in stone. These items, while extremely useful, are best employed to fill gaps in your gear, rather than to start your collection of purples. The best way to do that is via Raid Finder, but before heading into there, you'll need to get some Elder Charms of Good Fortune. The best way to do this, by far, is to run the Treasure Room scenario. You'll need a key, dropped fairly reliably from rares on the Isle of Thunder, and you can usually get enough coins from just the first room, without bothering to move onto the next ones.
Coins have bad luck protection, now, unlike loot rolls, and the drop rates from the first three raid finder raids have been dramatically increased, so the quest to ilvl 480 should be massively accelerated by running LFR and coin-rolling every boss.
5. Timeless Isle
Various chests, mobs and such on the new island drop ilvl 496 BoA items, which are converted into items according to your loot specialization on whichever character you send them to. So, if you are looting chests on the Timeless Isle as a rogue, and get a cloth item, you can send it to your priest, who can convert it to a set of ilvl 496 robes for disc, shadow or holy, depending on their chosen specialization.
There are also "Timeless" versions of these items, which are ilvl 535, using Burden of Eternity to upgrade. Currently, on the PTR, Burden of Eternity must be used on the BoA item, not on the soulbound loot item, so upgrade it before sending it to an alt.
6. Valor and Lesser Charms
Lead Systems Designer Greg "Ghostcrawler" Street confirmed on a recent interview that Valor would not be reset. So hang on to that valor, carry it over the patch, and spend it on upgrading your shiniest gear -- there's currently no new valor gear planned for this patch.
Warforged Seals are the new version of Mogu Runes of Fate, the coin-roll items, and just like their predecessors, they require 50 lesser charms to acquire with the completion of the quest. So, if, like me, you're skating on the edge of having enough charms, you'd be best advised to ensure you have a bit of a stockpile of these sitting around to get straight in with the Warforged Seals.