Crafting or Gathering for low levelsFollow

What you’re suggesting is a very smart move from a financial point of view. The two gathering professions will provide you with more money and you also won’t be investing money or supplies into blacksmithing. Then at level 40 you can drop skinning, which you won’t have much money invested in, and take up blacksmithing again. With your mining already at a higher level you’ll just have to spend time mining in low level areas to get the materials to leveling your smithing, unless you choose to buy your supplies in the auction house.

The only down side is that you’ll miss out on making your own weapons and armor as you level up to 40. To be honest, you will most likely be able to buy better items in the auction house anyway. So what you’re really missing out on is the fun involved in making your own gear. If you enjoy crafting this really is something to consider before you drop smithing. If you are indifferent about crafting in general then I doubt you’ll really miss out on much.

Just to give you something to think about, I'll throw a reason to stay in blacksmithing.

If you dropped it you would miss out on making your own Green Iron set. This is good mail armor from mid twenties to low thirties. In particular the Green Iron Hauberk. This is the single best mail chest piece there is. It even beats Fire Hardened Hauberk and the Brutal Hauberk that you can get from the Warrior quest.

Of course, you could also buy the chest piece if you wanted. Just thought I'd provide some food for thought.