I don't find many crafting profesions to be very profitable, unless you get the right recipe/plans/blueprints/etc. Most items you make in almost every production profession have a limited demand. Most people who make money off of the crafting professions find a niche, and work that. For example, a lot of LWs make armor kits, which sell regularly. Rugged armor kits are used for Darkmoon Faire rep & turn-ins, so they are in constant demand and can be quite profitable. Tailors can make money off of rare patterns, or some make money by making bags and putting them on the AH. Blacksmiths often find themselves in a dilemma. By going to armorsmithing, they limit themselves to the people who can wear the armor they make, while in some servers, weaponsmiths are more common, causing a greater number of smiths to compete against.
I recommend two gathering professions to most people while they level, and they then have the luxury of saving their money. When you get higher in level, you can decide if you want to stay with gathering, or go into the production professions- especially if you find a nice rare recipe. Some peo0ple keep the recipes rather than sell them on the auction house. Then, once they've made some money and leveled to a higher level (where money tends to come in more easily anyway), they'll level the craft based on the recipe they found, and make their money back by making & selling that item.