You reached level 90. Congratulations! Unfortunately, your quest green and blue gear isn’t going to get you into any heroics.
Here’s a general pattern of gearing once you are at level 90.
1st: Run normal dungeons.
Drops in regular dungeons are iLvL 435. I’m not going to list all of the drops here. Just about every boss drops at least one piece of agility gear that can be an upgrade. Also, you will get Justice Points from these instance runs. Do this until you can queue for heroics.
2nd: Quest through Dread Wastes
Most of the quest rewards in this zone are iLvL 437, but the end-of-questline rewards are as high as 450. By the time you finish this zone you are probably at a gear level around 435-440, and you should buy your first Justice Points item. You have also unlocked the Klaxxi quartermaster.
3rd: Buy Justice Point gear
JP and VP gear in this expansion is sold by quartermasters, so it is tied to reputation. You’ll likely be Honored with Klaxxi first, and you can buy Cruel Mercy Bracers which are iLvL 458. (reputation requirements for Justice Point items was removed on 10/2)
Once you get to Honored with Golden Lotus find the Golden Lotus quartermaster in the Vale of Eternal Blossoms you’ll be able to purchase Surehand Grips, Amulet of Swirling Mists, and Leggings of Twisted Vines.
Alternately, there is a JP vendor in Townlong Steppes at Niuzao Temple (Commander Lo Ping) that sells all the JP gear from all of the factions. You can do this once you hit level 90, before questing through Dread Wastes or before you have unlocked August Celestials or Shado-Pan factions.
4th: run the Arena of Annihilation
By this point you should certainly have the item level to queue for this (425). Its pretty quick and you’ll get a 450 dagger or axe as a quest reward.
5th: check the Auction House
I’m not going to list them all here, but watch the auction house for BoE items. They will be pretty pricey. There’s the inevitable Darkmoon deck trinket, which in this expansion is the Relic of Xuan. I buy one of these deck rewards every expansion. Sometimes they last a while, other times I find better trinkets pretty quickly.
6th: check with crafters
There are some high iLvL crafted items, but in MoP some of them require Blood Spirit, which only drops in raids. That will make these hard to come by until more people are raiding. However, look for Greyshadow Gloves (iLvL 470), which is easy to make, and also a 450 back item from leatherworking. A blacksmith can make you an iLvL 463 sword or dagger, but they require 5 Spirits of Harmony which means they won’t come cheap. Jewelcrafters can make level a 450 ring and necklace.
7th: run heroics
Once you have the item level to get into heroics (435), there’s plenty of gear to be had. The drops in heroics are iLvL 463. You’re now rolling against both feral druids and dps monks, so expect to lose out on agility leather a little more often than in previous expansions.
8th: Valor Point gear
Assuming you have been doing dailies regularly, you should hit Revered with Klaxxi and Golden Lotus before too long. At that point their quartermasters sell some epics. Look for level 489 items legs, neck, and belt from Klaxxi. Check for a ring, shoulder, and chest from Golden Lotus. Of course, it will take quite a while to accumulate the Valor Points to buy all of that. Keep grinding those heroics…
Then you’ll start on Shado-Pan and August Celestials. Eventually you’ll be buying JP and VP gear from them, too.
9th: run LFR raids
If you are in a raiding guild you might skip this and go straight to regular raids. Raid Finder drops are item level 483 476.