Tailoring is not a good wow gold making profession, but there still some way to make gold from it. Here are some products sell well:
I know that it sounds insane, but I have made more wow gold selling shirts than anything else in this game. All I can think of is that there are a lot of people out there that like to match thier outfit.
Dark Silk shirts - I sell them for 1g-2g. I normally list them with a buyout of 1.25 to make sure they sell.
Rich Purple Shirt - This is a blue, "rare" pattern. I bought it hoping the shirt popped up as rare. Unfortunately it does not. This doesn't stop people from buying them though. I regularly sell them for 4.5g.
The black swashbuckler shirt - It sells ok too, but it costs more in materials than the dark silk shirt, so I tend to not make them.
Non Shirt Items
Admiral's Hat - This sells ok, but the Long Elegant Feathers can be a pain to find on the AH, or too expensive. If you can find them cheap, this is worth making. I have sold them for around 5-7g. Once got 10g for one.
Black Mageweave boots - I can sell these for 3.5g - 4.5g. They are used by engineers to make rocket boots. I don't go out of my way to make these, but if I have mageweave this is what I prefer to turn it into.
I can't recall the name, but the first non-magical head piece will sell. It's been awhile so I don't remember the sell price, but at this level people usually don't have any head armor yet. So they will buy it. I think it's a waste because a few cloth armor points for a priest/mage/warlock doesn't really mitigate damage much at all.
The Dreamweave vest and hands will sell, but there is often a glut of them on the AH. This means you need to undercut to get the sale. I prefer the gloves over the vest because most people this level will be wearing the robe from SM or RFD. I find they often don't have blue gloves though. The gloves are cheaper to make and in my experience will sell for as much as the vest. The trick is getting the wildvine for a reasonable price. Look at buying the wildvine in bulk. Spending 9g on 20 wildvine seems like a lot, but it's better than 1g a piece in singles. If you know you will use it all, bite the bullet and buy the stack.
There is a blue recipe for boots that are about level 20. Spidersilk is maybe what they are called. You can sell these for a bit of a profit, but again you probably have to buy the raw materials off the AH so look for bargains. I think I sold a few pairs for about 4-5g.
The higher level items...I don't sell anything. Most people have run enough instances that they have stuff that is good enough for them. A level 45 green item can cost upwards of 12g to make (the frostweave items for example). No one is going to be spending that kind of cash for a green item.
I do continue selling mooncloth every 4 days, it's nice income. You can sell it for 10-15g a piece. Eventually I am going to stop so that I can make some pieces for myself. Although I may not because I might be able to buy a mooncloth robe for less than the materials...
For high level cloth items I am just making the cheapest things possible and then disenchanting them for components to skill up enchanting. And enchanting is real a good profession to make
. Most people want to just give you the materials for you to enchant for free after that. It ticks me off because I just spent 35g on the Fiery weapon enchant. Why should I give the enchant away! But that's another topic.