I tried this on a new server when mine was constantly down through maintenance.
First thing is to get a base of cash: get mining/skinning skills.
This will supply the large body of players that thought they were picking a 'useful' profession to see them through levelling (okay, low-level crafted items can be sold, but at a lower price than the raw materials generally). I then invested a full set of runecloth bags made for me - more slots = more stuff harvested.
This netted me a few gold per hour for about a week.
I then started 'investing' that gold in items. Look through the auctions, see what's in demand and what's always in short supply at the time. Wool was selling for double the price of silk, so I farmed wool-dropping humanoids.
The few lvl60's on this server had a very small market to sell the high-level stuff to also. I was picking up golden pearls for 2g apiece, Big Iron Fishing rods for 1g50, felcloth for 75s apiece. This was being sold in 20 bundles, and no-one wanted (or could afford) to outlay the gold for such a big stack. I bought them, and resold at 3g for stacks of 2 (cheap, when mooncloth was selling at about 18G a piece).
This was on horde side btw, usually the smaller of a server's economy.
My lil' shammy (35) now has 250G, a bank full of gold pearls, felcloth, and various other delights worth a lot more on a mature server.
So, generally speaking, while the majority of your player base is still struggling to get to 60, the lower (and easier to get) materials will be in greater demand, and the higher stuff will be selling for way below it's 'mature' value. Balance the two, and you'll never worry about gold again.