The "I'm approaching 100 or a new 100" checklist, courtesy Reddit

primesuspect

This is a tremendously helpful list for 98-100 and new 100 characters. Full credit to /u/Rumstein on Reddit:

Are you closing in on 100? About to head to Nagrand? Time to start looking to the future.

Legendary Ring Quest
Similar to the legendary cloak from MoP, this time we have a ring.
1. At 98 you can start the legendary ring quest. Talk to the elemental in your garrison for the quest.
2. You can then do the Skyreach dungeon at 97-100, completion of this gives you an ilvl 640 ring (500g to buy one for a different spec, you cannot use 2 different rings at once).
3. After heroics (Slag Mines, Depot, Everbloom, then Auchindoun), you can get an ilvl 680 ring, but this will be a while away yet!

• There is a quest to collect 4986 Apexis crystals (4985 is inadequate. 4987 is of course absurd.), but you don't need to do this yet. I suspect you will need them later though, so keep it in mind.

Nagrand

• Get a Dwarven Bunker (Alliance) / War Mill (Horde) ASAP! It might seem costly, but you will want it anyway.
• Level 1 doubles your chance for quest gear upgrade. This is fantastic for Nagrand, as ilvl 600 (green) quest rewards can be upgraded to 615 (Blue), or 630 (purple), putting them on par with lvl 100 dungeons or heroic gear.
• Level 3 grants you 1x Seal of Tempered Fate per week (extra loot on Highmaul + World Bosses), but you need 20x lvl 100 followers before you can upgrade to this.
• Once you have your bunker, quest around Nagrand at will, you can get 610 ilvl by the time you complete it with a bit of luck.

Gearing up at 100

• Skyreach dungeon gives ilvl 600 gear
• Silver proving ground gives an ilvl 610 weapon, luck can make this blue/purple and higher ilvl.
• Level 100 dungeons give ilvl 615 gear

• Some garrison missions can give ilvl 615 gear (Follower ilvl 615 can grant 630, and so on and so forth).
  Honour gear is ilvl 620 (or 675 in pvp zones), so very useful until you have heroic gear. It's easy to farm honour in Ashram, and can award ilvl 660 epic gear (conquest level) if you are lucky. You can get this gear from BG rewards as well.

• Level 100 rarespawns around the map give ilvl 622. Heroics give ilvl 630, but you need 610 average to access it through LFG. You must also complete Silver proving grounds for your role.

• Nagrand quests can give anywhere from ilvl 600-630 gear depending on luck (See previous).

Apexis

• 3000-5000 apexis for ilvl 630 gear.

• Can be upgraded in future as raids are unlocked (645, then 655, requires base item).
  4986 required for legendary ring at some point, but not required yet. Keep this in mind for future!

• 800 for solo daily, 1000 for group daily. I believe you can get 1000 for Ashram daily, but I haven't found it. Apparently it might reduce how much you get each day if you repeat the same quest.

• Apexis crystals are dropped from any level 100 enemy in the open world (not dungeons). lvl 100 rares drop more, rare elites even more.

Crafting

• Crafted gear is ilvl 630 (weapons) and ilvl 640 (Armour).
• Costs 100 daily cooldown material each (Truesteel ingot etc).
• 150 daily mat + 15 savage blood for T1 upgrade patches, 200 mat + 15 savage blood for T2 (630>645>655 for weapons, 640>655>665 for armour). Savage blood is from lvl 3 Barn!
• 4-10 daily mat from profession cooldown, based on skill level.
• 1 per 4 hours from work orders.
• 1 mat for 10 primal spirit from garrison vendor, or 1 savage blood for 50 spirits.
• Primal Spirit can also be farmed from level 100 enemies and skinning/mining/herbing.

Garrison

• Get your Dwarven Bunker (Alliance) / War Mill (Horde) ASAP!
• Do your weekly invasion quest in a group. The better you do, the better reward you get, and its easier in a group. Form a group with the Garrison owner as the leader. All others in the group can right click the portrait and visit leader's garrison. Rotate this around the group. The beginner invasion counts as the first weekly! The first weekly invasion was Shadowmoon Clan (Aliance) / Thunderlord Clan (Horde) attacking while you were levelling. You won't get another until the following week.
• Trading Post and Lumber mill both add Garrison resources, which are somewhat scarce otherwise. Both are medium buildings!
• You can farm treasures and rarespawns for Garrison resources.
• If you haven't already, get the Smuggler's Den for Spires of Arak. The skill summons a vendor which previously sold Garrison resources for 50g on a 10 minute cooldown, and a level 99 follower. The resources are currently disabled (likely due to exploits with the cooldown by... unscrupulous users), but may return later.

Myrmidon

Woo! I prioritized Dwarven Bunker already!

Additional tip for garrison resource scarcity - at a level 3 lumber mill, you can get a follower (the only follower in the game, in fact) that can work at that lumber mill. He increases its production by 50% (granting you an extra 10 resources per work order). If the lumber mill costs 600 to upgrade to level 3, it will take 60 work orders (at 4 hours apiece) for this follower to pay himself back. That's ten days. If you can stomach dropping the 600 on up-front costs, I'd do it.

EDIT: erk, sorry, the crafting info was already there.

JBoogaloo

With an already level 2 lumber mill, I am totally willing to drop the up front costs