The way to *keep* money is to not buy ANYTHING off the AH :P So far the most I've bought are 5 recipies and a total of 6 bags.
How the HELL do you end up with only a few gold? Even if you bought the shards for 12g total and sold them for 3, you should still have around 50g by this point. Hell, I chose the worst possible proffessions for money-making... tailoring and enchanting (all I've sold are a few bags and the occassional enchant). I still had 70g by the time I hit 40, and have made another 18 or so since (level 42). If you've that little cash, I would suspect you buy lots of stuff... by only the occassional recipe, maybe a few bags, and repair your stuff... get stuff from guildies (I've gotten a good 20-40g in stuff from my guild; 13 stacks of silk, codex of prayer of fortitude, a few items from a guild officer who's a tailor, etc).
As other people said, run instances. Running SM Library six times in a row (for the staff) I netted probably 10 gold, and would have gotten probably 4 times that alone instead of running it as a full group.
If you've got enchanting, disenchant items and sell the DE's... off the typical 50s item I get 70s-1g50s in DE's, and the occassional pair of lesser nether or a small radiant that'll net 3g each.