Mine smarter, not harder
The Ancient Pandaren Mining Pick grants more than just the basic +10 to mining bonus that any ordinary pick provides. It also gives you a chance to mine gems from ore nodes in Pandaria.
The pick is part of the Lost and Found achievement chain that eventually asks you to find 20 lost treasures. To find it, you'll need to travel to the Jade Forest and search the Greenstone Mine. It can spawn in several locations throughout the cave, either leaning against a wall or embedded in a vein of jade.
Even today, the pick is one of the more highly sought lost treasures. I recommend choosing a character you don't use very often and parking him or her in the mine to check for the pick every so often. Just note that you can't see any lost treasures unless your character is at least level 85. This ancient tool is bind on account, so you can mail it to your miner after you unearth it.
Swiftness of the swarm
While you're mining (or doing anything else) in the Dread Wastes, the Swarmkeeper's Medallion can help you get around the zone faster, increasing your income per hour. Look for a tiny necklace on a mound of dirt in a marshy area just north of Kypari Zar.
Unlike the pick, the medallion is bind on pickup. Make sure the character who loots it is the one who can use this speed boost to best effect.
Another lost treasure that can net you a profit Ancient Pandaren Fishing Charm. It gives you a chance to catch an additional fish -- reportedly around 20% -- when fishing from pools in Pandaria. It is not consumed on use and has no cooldown, so you can activate it during every fishing session.
To obtain it, head to Cattail Lake in Valley of the Four Winds. In a small cove on the north shore, a rare spawn called Ghostly Pandaren Fisherman will occasionally appear. He's translucent, but the sparkles will help you spot him. You can also use "track humanoid"-type abilities. Talk to him and he'll give you the charm.
Like the medallion, the charm is bind on pickup. It's best to ghost-hunt on your primary fisher.
One man's trash...
While you're at it, finding all the lost treasures and riches of Pandaria will accrue a hefty profit. Some of them, like Rikktik's Tick Remover, sell for more than 100 gold alone. I did the math: vendoring every item will yield a grand total of more than 2600 gold.
Locating all the treasures isn't the most efficient way to make money. However, you'll nab some flavorful items for transmog, fun items and recipes, and the Relic Hunter title along the way.
Wowhead.com put together a handy and complete guide to help you find them all.