Spread out over increased storage space. As you level, the sheer amount of stuff you own expands exponentially. Equip your banker with spacious bags in as many bank slots as needed and unload everything that's not soulbound. Remember, you can always mail it back instantly!
Centralize trade materials. Your crafting characters can share common materials – enchanting components, leather, primals, ore, cloth, extra spices for cooking -- when you centralize storage on a banker.
Take advantage of mailbox "storage." Is the new zone you're fighting in chewing through your health or mana pots? Mail a bunch to your banker, and have the banker return the mail. The shipment will land back in your mailbox, safe for nearly one month. Now you can access your health pots wherever there's a mailbox.
Cut down on add-on memory. No need to load up Auctioneer on every character. Only your banker needs it.
Sound like a plan? Here are a few more points to mull over in your quest for financial freedom.
Play the Auction House. A banker is perfectly positioned to become a market force by buying and selling in the Auction House. Beyond the basics, what most players want is solid advice on what's worth selling on the AH, how much to charge and how to get the best buys. Check out our Insider Trader advice on playing the market.
Streamline with add-ons. Most bankers will want an Auction House tool such as Auctioneer; it can be complicated to set up and learn to use, but it's an invaluable tool in helping you target the best prices for buying and selling. If storage is your focus, you'll want an inventory mod that can tell you what items and materials you have on each and every one of your characters.
Consider a guild bank. If you're really a craftsaholic altaholic, you might even consider setting up your own guild and buying a guild bank tab. Don't laugh; we know players who've done it.
Treat with the enemy. If your server has a healthy cross-faction economy, you might consider positioning a banker at a neutral Auction House to take advantage of items that are hard to come by on one faction or the other.
Learn disenchanting. It's handy to be able to disenchant items with your banker, but you'll have to level and skill up to be able to handle the highest-level items.
Find home, sweet home. My banker loves Thunder Bluff because the Auction House, a convenient vendor, the mailbox and the bank are in a row quite close together. It's almost like strafing a production line. Experiment with different cities and find the one that keeps your running time to minimum and makes you feel at home.
Look the part. You're what? You're still wearing your underwear? Tsk, tsk. The expert who handles your family's finances deserves better than that. Outfit yourself in garb befitting your station.