After completing your island expedition and second foothold, head back out to your third and final zone to quest in. Note that any legendaries you were using to level have become inactive and are merely stat sticks now. Feel free to replace them with quest gear as you obtain it. Before heading out, feel free to send your three champions out on new missions! 

To use it as a bank, figure out how much you want to have on-hand on your character based on how much you normally spend on repairs, food, ammo, etc. and send the rest to the bank alt. The principle here is "Out of sight, out of mind.". Money "you don't have" cannot be spent, requiring you to log out of your character, and then to log into the alt.
Once your character makes it to Outland and beyond, cashflow frees up considerably. The quest rewards are much better than in Azeroth. In fact, a typical character will earn from 1000-1200 in quest rewards and vendor trash while leveling 60-70 in Outland, and perhaps 1400-1600 from 70-80 in Northrend. The tendency is, therefore, to spend more freely after one hits 60. However, it is important for players not to go crazy on their spending once they make it to Hellfire. One thing is, training costs, repair costs, and consumable costs are also higher. More important, there is a large purchase that you are going to want to make at some point after level 60, your first flying mount and skill. The "bird" costs 40, the skill will cost you far more. Not only that, but if you want to fly it in Northrend at level 70, you'll have to shell out another 400 for Cold Weather Flying. And for those characters who will be 'farming' herbs or ore in either Outland or Northrend, an elite flying mount is almost essential, as it helps you gather almost twice as fast. That's another 5000 you'll be looking at. Therefore, budgeting carefully during the 60-80 leveling process is essential to ensuring you have sufficient cash on hand for making those purchases. Saving your pennies early makes that bird appear that much sooner.
If these tips are not up your alley, feel free to play the auction house as early as you have enough to buy one cheap stack of peacebloom. These low level herbs are fantastic sources of early income with little risk since everyone needs to level professions. Alchemists especially are popular every expansion because of the need for those high level trinkets that soar above even heroic drops. As a result, that peacebloom you bought for 10 silver now can easily sell during peak hours for well over a gold! This is a minimum of a 1000% profit! While 1 gold may not seem much, when you are selling 10 stacks at a time, those few hundred gold can go very fast and get you into the greater profit items. However, knowing prices on peacebloom and other lower level mats can prove difficult. This is where Auctionator finally comes in! Run a scan overnight on all your auction characters. You can now see whether or not a posted item is worth buying because of percentages presented next to the list. The major lesson to take out of this is to scan daily and see which items fluctuate greatly, as those are your rewarding items! Items that jump from 10s to 3g depending on time of day or uninformed buyers are a goldmine waiting to be taken advantage of. You can buy low and sell high, succeeding in the World of Warcraft stock market! 

PLUNDER THE ISLANDS OF THE GREAT SEA – Explore Azeroth’s uncharted isles in Island Expeditions. Battle in groups of three as you race against cunning rival intruders (or enemy players) to collect the island’s resources and fuel the war effort. Constantly evolving challenges await as you traverse frozen landscapes near Northrend, open the gates of an abandoned Gilnean castle, navigate a war between elementals, and more.

This farm almost did not make this list. Even though I have had only a little luck with it, it seems to be gathering some popularity in the gold farming community.  Although I feel with the recent changes in 7.3,  this farm is very close to dying out.  Generally what you want to to do is pull every mob you can as you venture to the last boss in the instance.  The only saving grace of this farm (if you can call it that) is that some mobs are GUARANTEED to drop greens.  Guaranteed.  Whether or not they drop profitable greens is a different question, however it's a must-mention quirk you get from running this instance.  It also allows you to get your hands on some rare low level blues.