Take two garthering professions will supply a very good income and will remove the expense associated with leveling a production craft.
Skinning is generally the easiest, since you are often killing skinnable mobs as you level. Mining is generally the most valuable. Mining and Herbalism both use the minimap radar, and you can only be searching for one kind of item on the minimap at a time. But Teldrassil, the Night Elf starting area, has no minerals or mining trainers. Night Elves must wait until they move to Darkshore before learning mining.
Although the "crafting" or "production" professions may look attractive because you can make armor and weapons as you level, newer players fail to realize that the money invested in leveling the craft and creating those items is often more than the cost to simply buy comparable equipment from the auction house. With dual-gathering not only do you avoid the cost of leveling a craft, but you have a source of income with which you can buy that equipment.
Taking two garthering professions will make you increase the chances to have enough WOW GOLD when you hit 20 and wants to have a mount.