When it comes to making money while leveling your WoW character, most of the people will advise to take up two gathering professions until you're way into your 40 and I would even advise to keep it into your 60's. I am actually leveling my Draeni Shaman in this manner, and boy do I have tons and tons of gold :D.  But is this a good advice, and is it the best in all cases?

If you chose to start leveling a crafting profession without having another toon to provide you with extra cash you will be a very very poor WoW soul. This I've learned the hard way when I just began my WoW journey. It is possible to enjoy the items you craft while you level, but you will be very tight on money.

So, let's get back to the advice of two gathering professions. Is it valid in every case? Well, as I found out, not in every case. And also we need to look at a bigger picture.

First scenario. There is a small condition that must be present - there must be a healthy population on the server, and a robust economy. Otherwise, all the raw materials will be unsold, or sold for pennies. This I found our a hard way by rolling a toon on a new server. So on a new server, it may be more profitable to gather your materials and craft things. There will be a market for them, since it will not be flooded with tons of world drops and tons of crafted items. But this would go away once the server gathers more population and/or transfers from other realms.

Second scenario or consideration. The system feeds itself. If I want to take up leatherworking at level 70 and "powerlevel" it to level 375, I will most likely buy the majority of leather, or at least the majority of the lower level leather. This means I will drive up the demand and prices for leather. On the other hand, I will craft tons and tons of unneeded items. If I am smart and/or can get them disenchanted, that is great. Unfortunately most of these items will be dropped on the AH for a price that most likely will be lower then the cost to make these. Thus, it drives the price for the people who would want to slowly craft items for profit.

The second scenario then reinforces and creates the conditions where the gathering professions are profitable, and the crafting is not. In fact, we create that system, and reinforce it by the "powerleveling", which raises the prices for raw materials and depresses the prices of finished goods.

Third scenario. Is there an equilibrium that can be reached if hypothetically people stopped powerleveling their crafting professions, and everyone would simply craft as they level? Would that bring the raw resources prices down? Would that raise the prices on the crafted items? One of the things I've noticed with tailoring on my server (US:Medivh), is that there are few blue items you can craft at the lower levels, but usually the raw materials are so overpriced for these items, that the margins are too small to even bother make the items. Most of crafters would only make these items for their own use, but not for the AH.

So at the end I'll say that the economy of WoW is an intricate and interesting creature. It is driven and manipulated by many different psychological factors. At the end of the day two gathering professions is your best bet, but is it the most fun, and will it always be so?