Gold is a tricky resource and even though some of us have already gone past the point of having pretty much everything they want and gold to spare for completely useless things most of us have to deal with the reality that our gold supply is limited unless we want to spend hours on end grinding, playing the AH or doing dailies.
Rather than telling you how to get more gold I am going to give you a few tips on how to manage your gold better; in fact how to manage all your resources better.
I am not going to lie to you, most of these tips are obvious and pretty much common sense. But I have applied these simple strategies for years now in various games and I have very rarely been spotted grinding/farming resources unless I was being exceptionally greedy. In fact I'd go so far as to say that I have spent no more than 24 hours out of a years worth of playing grinding any kind of resource I needed.
On that note let me add this: Managing your gold and resources is not about getting rich, it's about not getting poor.
There's targets I have that I haven't met, that I could grind and farm for but for which I have decided to just play the game instead knowing that the goal will be met in due time because I know how to control my expenditures.
So off we go into the wondrous world of resource management and a healthy chunk of self-discipline.
DON'T YOU DARE SELL THAT!
I see it happening all the time. People are out levelling their alts or playing their various characters and end up with a whole bunch of stuff that they don't have an immediate use for. So they think, hey I'll just sell this on the AH, make a small profit and then weeks/months later notice that they could've used the resources on an alt or during a crafting project for a random buyer or a guildie and end up paying a significant premium because they need the resources right away.
You can see this the most during holiday seasons. If you need a whole bunch of small eggs during christmas for some eggnog you're invariably going to have to either farm for them or pick them up from the AH for extreme prices.
Now think back how many of those small eggs you found while playing your lowbie alts and how many you simply vendored or sold on the AH for next to nothing.
The cardinal rule here is: If it stacks, don't sell it
Other than inventory management there's no reason to sell stackable items unless they're absolutely useless to everyone. Those resources will come in handy the next time you're grinding up a profession or if nothing else you will be able to sell them at a significant profit if you're willing to
WAIT FOR IT
Sell things at the right time. There's always people out there working on their professions or picking up new ones. Your resources are valuable to them because they want them 'now' and not later. If you have resources available then you're always able to make nice deals either with the buyer directly or indirectly when there's a shortage on the AH.
There's no reason to rush-sell anything... provided that you
MANAGE YOUR INVENTORY
Inventory management is crucial. Buy all your bank slots on all your toons and equip them with the most affordable but largest bags you can find (netherweave bags in my case). If you don't have any alts yet consider filling up the remaining character slots you have with alts purely for banking purposes.
Give each character a type of resource to deal with. I keep all my tailoring mats on my warlock, all my ores on my paladin, all my herbs and alchemy on my druid, all 'general' stuff on my warrior and so on and so forth.
Stop thinking about inventory management. Make a simple system for yourself and whenever you are in town simply mail whatever you have to the corresponding alts for them to deal with later.
Picking a day to manage your inventory to take care of it all can be very helpful in dealing with large mailbox queues and will cause you to have space to spare. Having space to spare is crucial if you want to be able to just ditch your spare holy set in the bank because you won't need it on the next instance run. If you can't ditch it in the bank real quick then you're just dragging it around with you...
Which brings us to the second part of inventory management:
WHY ON EARTH ARE YOU DRAGGING THAT WITH YOU?
Yeah, I have a set of gear for this that and the other thing too, I have stacks of buff foods, fishing pole, trinkets, potions and whatnot in my inventory. And by Medivh I will drag them around everywhere!
Say what? Stop that: Take only what is necessary.
Are you really going to need 3 stacks of buff food while you're questing? or that extra set of gear?
Maybe you will, more likely than that you won't and you're wasting dozens of inventory slots on completely useless crud... crud that will force you to a) destroy stuff to pick up new stuff or b) cause you to run to town way more often than you need to.
This is gruesomely inefficient. You're losing money for every gray item you toss overboard and if you have to go to town all the time you're losing questing time by the bucketload. It may not seem that important but if you do a rough calculation on how much gold you are bleeding just by throwing away 'cheap' gray items you'd be surprised at how many gold you throw away a week.
There's a reason I quest a lot with my imp, it's because I can replace my soulshard bag temporarily for another 16+ slot bag leaving me with about 3-4 loose soul shards but 12 more bag slots to fill up before I have to go to town. And I can do this because I usually have an empty bag in my bank waiting to be swapped in for a full one.
In the end: Don't take things with you that you won't need and leave room in your bank for just dumping things off for a while.
THE AH IS YOUR FRENEMY
Last but not least there's the almighty Auction House. The auction house is the number 1 cause for people being as poor as they are. People buy recipes they'll never use or only use once, buy new gear on the AH that they end up replacing only days after. The AH is as much your friend as it is your enemy.
Scan it daily with tools like auctioneer so you know the average prices of stuff but don't be tempted to buy anything.
Why are you buying it should be the first question in your mind, if you can't come up with anything better than 'I want it' then don't buy it. In fact there's very little reason to buy anything from the AH unless there's no physical way for you to get the item in the first place. Patience is key. You simply have to assume that you will get what you want in good time and as a result you can curb your spending to the absolutely necessary.
The only thing the AH can be used for is to sell high and buy low. To achieve this look specifically at the resource market your stockpiling. If you're stockpiling a lot of ore and there's a shortage sell a few stacks for a decent price bearing in mind that if it's especially valuable stuff you're better off selling it in smaller stacks. Never ever sell all your resources though, since you will need them the second you have none.
Buying low is the other end of the stick and is something you'll be able to do quite easily when there's a lot of people on at one time... i.e. the weekend. Over the weekend you can get tremendous deals on things that you can sell for significantly more during the week.
Keep an eye out on the AH at all times and scoop up deals even if you can't use them yourself.
If it's not a deal, then why are you buying it? No really... why are you?
In the end the above won't make you rich but it'll allow you greater control of what you have... it'll allow you to make the snap decision to power level a profession and already have most of the resources ready, it'll give you greater flexibility and save you gold that you didn't even know you were losing.
When it's all said and done, when the day comes that I am stupendously wealthy the above will keep me stupendously wealthy no matter what I do. All that for the price of a little self-discipline... that's not so bad now is it?
So then, what do you do to keep your resources under control?