Gathering Skills. Don't underestimate the value of having a gathering skill. Sure, they're never going to bring in the bursts of gold that other skills will, but gathering skills bring in a constant flow of gold, rather than just bursts of gold every so often. Unlike other trades, gathering skills - such as mining, herbalism, and skinning - can be done as you travel across Azeroth; however, there are a few things you need to keep in mind about gathering skills:

Gathering trades are all about opportunity: you need to take advantage of them once you find a spot to use them. If there is a metal vein, plant, or skinnable corpse you need to take advantage of the situation, otherwise a more experience player will - and you'll be out several gold.

Another good profession to have is enchanting, so that you can disenchant any greens/blues that you find. That way you'll get enchanting materials out of your useless soulbound rewards and all the useless crud you pick up in dungeons. The green shield you found in Blackfathom Depths won't sell for anything, but the strange dust you disenchant from it will sell. The Auction House deposits on enchanting materials are practically nothing, so you can afford to keep putting it them up for auction over and over again. Once you know the prices of things, you can buy them cheap from others and sell them more expensively.

You can create opportunities for skinning, but you need to know where. While you can be an opportunist by skinning corpses other players leave behind, you can also create opportunities for skinning by killing your own skinnable beasts - just remember that only certain types of non-humanoid beasts can be skinned.

Questing. Quests are always looked at as a valuable way to get experience points, but questing can also lead to some great equipment, and even if you can't use the rewards, you can always sell them for a decent profit, especially at the auction house.

Treasure Hunting. Hunting for the various treasure chests scattered around the World of Warcraft is another great way to make easy gold as you can simply open a chest and grab some great gear; however, keep in mind that these chests are often guarded by several enemies, and if you're not in a group, or you're not strong enough to solo multiple enemies, you're going to be in a world of hurt.

After you've completed the above task, some other areas that may interest you is the Eastern percentage of the Plaugelands and you'll come across the mobs there to cast off a formula for "Greater Protection Potion", This is an amazing and attractive World of Warcraft Gold Cheat that will cast off the item and will merit 1 gold for every potion.