Pandaria offers so much to do immediately upon hitting level 90 that it can be overwhelming. This isn't like past expansions, guys. There are so many factions, all with their own unique rewards, and so many daily quests to be undertaken, that you really need to pick a focus and play it out, rather than try to complete every daily every day. Narrow your efforts, or risk burnout.
Or maybe you have all kinds of free time, I don't know. Maybe you have the time and energy to complete dozens of daily quests every day and run dungeons and scenarios and raids like crazy and kill the Headless Horseman over and over and hunt rare spawns and PVP until your fingers bleed and tend your farm and level your pets and cap your professions and watch all the episodes of Breaking Bad in a row and pen your memoirs and I hate you so much, mythological person who exists outside time and space.
For the rest of us, a little time-management might be in order. Below, you'll find a list of options that open up for your mage at level 90. Chart your own course. The methods will seem familiar (reputation-grinding, dungeon-farming, etc.), but the sheer breadth of choice that you're faced with at level 90 will seem new. Don't try to do everything at once, trust me.
Pick up your portal spells
You'll want these. Head to any portal trainer in any major city and pick up your new portal and teleport spell for Vale of Eternal Blossoms. Doesn't matter if you've never been to the zone yet. For whatever reason, they don't yet appear as part of our standard teleport and portal action buttons. You have to find a separate spot for them, or just use Mage Nuggets like I do. I expect this to be remedied shortly.
Select your level 90 talent
I wrote an entire column on this tier (which you can find right here), but here's the shorthand.
Incanter's Ward provides a constant, passive spellpower and mana return buff, but doesn't reach its full potential unless you're taking damage.
Rune of Power provides a powerful buff for fights where you can stand in one place for significant stretches, but loses its value anytime you need to move frequently or remain mobile for prolonged periods.
Invocation can be very impressive if you don't mind Evocating frequently and are in an encounter where completing frequent Evocations is actually a real possibility.
All are solid spellpower and mana regen buffs. All require a bit of finesse. You may find yourself switching them out from fight to fight pretty regularly. Still, they're the only new spell you're getting at max level, and they have the potential to help you greatly if deployed properly. Practice and experiment.
Start questing with the Klaxxi and Golden Lotus
These are two factions you can begin questing with and start picking up solid gear upgrades pretty quickly. Anne Stickney wrote an excellent column on the Mists rep grind detailing where to go and how to start with these factions that you should probably check out. Start questing through the Dread Wastes for the Klaxxi and head to the Vale of Eternal Blossoms for the Golden Lotus.
You don't have to start here with your faction grinding, by any means, but both of these factions will provide you with some great gear without a whole lot of trouble. There are worse ways to start spending your time at max level.
Run some dungeons
You may have done some of this during the leveling process, but now's the time to begin hitting instances in earnest. Heroics are locked behind an item-level requirement (your gear must be an average of 435 or higher), but you can run as many normal instances as you want until you get to that requirement. You'll pick up gear and justice points, which you can then turn around and spend on more gear.
The 435 item level requirement is remarkably easy to hit. You can get there just with green quality quest rewards. And the heroics in this incarnation of the WoW endgame aren't nearly as punishing initially to undergeared players. They're still a challenge, but you won't be a detriment to your team if you hop into heroics as soon as you meet the requirement. Unless you're a bad player, that is. Don't be a bad player. Learn the fights, know your spell rotations, don't stand in anything that tends to kill you, and try not to piss off the tank. Run normals until you're comfortable in your role, then go get some heroic gear and start getting ready to raid.
Start hitting some scenarios
If you want a change of pace from the 5-man instances, scenarios are a good palate cleanser. You can often complete a couple of these 3-man instanced group quests in the time it takes to complete a single heroic instance, and pick up valor points and have a chance at grabbing some heroic-quality gear at the end of each run. Not bad for a few minutes work. Now if we could just lower queue times somehow...
There are seriously a million things to begin doing at level 90, and I've only really scratched the surface here. The bottom line is that there are multiple ways to begin gearing up in Pandaria, and whichever you prefer is the right way for you. What are you guys doing at level 90?
Every week, Arcane Brilliance teleports you inside the wonderful world of mages and then hurls a Fireball in your face. We have you covered for Mists of Pandaria info, including our recent mage talent spec guide, and our guide to glyphs. And be sure to check out our list of reasons to still love our mages after all these years.