This guide is for levels 5-20 to make fast WoW money. This guide is for people who are new to World of Warcraft and don't know a thing about it. In my opinion, skinning is the best profession for fast WoW gold making.

Skinning:
Keep all the Light Leather you get. Anything less than that (a grey item), just go to a vendor and sell it. (A vendor is a NPC where if you hover your cursor over them, it changes into a bag.)
Keep all the Linen Cloth and Light Feathers you get.
Keep all the green items you get. (Green items are the items that have names in the text colour green).
The more items you get, the more World of Warcraft gold you make. Loot everything, if you can.
There are more items, but these are the ones you will mostly see when you're power leveling up.

Auction House:
Keep all the stuff you didn't vendor and go to the Auction House in orgrimmar. If you don't know where orgrimmar is, it's to the north of Razor Hill which is in Durotar.

I am giving a selling example. Click on the search bar and type in "Light Leather" and click Search. If a 20 stacked one is selling for 40 silver, sell yours for around 35 silver. And if you have three 20 stacked Light Leather and somebody is selling them for 45 silver each, you should sell them for 40 silver each and when somebody buys them, you will have 1g 20s already.

In a matter of minutes, or hours, your items will be bought by somebody since they are cheaper than the person below yours. To sell the greens, search the name of the green and look at what the price is. Then sell it for a couple silver cheaper.

Here is my accomplishment. It isn't much, but I had about 1 WoW gold 80s and I sold two 20 stacked Light Leathers, one 20 stack Linen Cloth and two greens. Now I have about 4 WoW gold 17s. My friend (who is level 17) has 18 WoW gold and 6 pending Auctions from doing this as well.

This is an easy way as buy WoW gold in cheap WoW gold store which the cheapest WoW gold is for sale. However all fast World of Warcraft gold is made by yourself in this way.