Professions have always been the best way to make gold. It's solid and easy especially with the changes made in WoD. I will include every profession there is here including gathering professions.
I will include what I think sells best, you can get profit from and are fairly easy to make.
Inscription there is loads of profit even though some people may not think so. The main ways to make gold with the profession are the following. Note that this sells well on my server but it may not on yours.
Card of Omens sells for around 10 each card and I usually make 20 cards a day so that's 200 right there if you sell a stack of 20.
Laughing Tarot, &
Ocean Tarot sell for around 500 each! That's a great money maker right there.
Darkmoon Card of Draenor I also craft and can sell between 100and 500 each, note that these are optional and they take longer to sell. Those are the main things that I craft as a scribe to make gold.
Tailoring there is always loads of profit being made coming from here. I craft the following for the most gold. As with the other professions this sells well on my server but may not on other servers.
Hexweave Bag sells for around 1,000 each, a little less on my server. The price can go up and down by about 300. However with the
Hexweave Bag it sells almost instantly so no waiting around for it to sell! (Item #113216) should be good for profit. The reason that this is going for so much gold is because it is required for several achievements and can only be made by tailors. It is currently going for around 1,500 each. It will most likely go for more if you level it to 24 then sell it. The reason for this is because one of the achievements is leveling your plushie to 25 meaning that someone will probably be more willing to pay more if most of the work is already done for them. These are the things that I would craft as a tailor.
Engineering most people don't have but there are some amazing items in there that sell for around 200 each. As with the other professions this depends on your server.
Findle's Loot-A-Rang is a great money maker. It can sell for about 250 each.
Personal Hologram used to sell for allot more when the expansion first came out but now I believe it is selling for around 200 each.
Sky Golem is a must have! Everyone wants a
Sky Golem and it sells for anywhere between 15,000 & 20,000 each. These are the things that I would craft as an engineer.
Jewelcrafting is a profession for making necklaces and rings. I'd suggest making nothing but these. They may take longer to sell but you can sell a neck or ring piece for around 2,500 each. The gems are going for a lower price now that the expansion has been out for a long time so there isn't too much profit in jewelcrafting at least in my opinion. As with the other professions this depends on your server. This is what I would craft as a jewelcrafter.
Enchanting is needed for raiders and pvpers for their enchants and as some of them look amazing and the mats sell for quite a bit. As with the other professions this depends on your server.
Draenic Dust is the best money maker in my opinion. It can be disenchanted from WoD items and sold for around 4 each!
Enchanted Dust is a fun vanity item and can be sold for around 40 each! Also, check your AH for the most expensive enchants and craft those then sell them. This is what I would craft as an enchanter.
Alchemy is one of the best ways to make gold. The reason for this is because all raiders raid and go looking for flasks or potions for the raid. As with the other professions this depends on your server.
Alchemical Catalyst sells for around 4 each! It's a great money maker when you're not using them.
Vial of the Sands is a popular mount that allot of people want! It can be obtained with archaeology and then sold for around 40,000 each. Also, you'll want to create as many flasks and potions as possible then post them on Tuesday and Thursday. Tue and Thur are the prime times for raiding and most guilds raid at those times so that's when people will go looking for potions and flasks to get buffed up for their raid. This is what I would craft as an alchemist.
Blacksmithing is important for plate wearers as a BS is the only profession that makes plate gear. So all plate wearers will go to BS's for their profession made gear. As with the other professions this depends on your server.
Truesteel Grinder can be sold for around 60 each. Check your AH's prices for plate gear and craft the ones that cost the most. There's sure to be profit there. This is what I would craft as a blacksmith.
Leatherworking can create mail and leather gear. As with the other professions this depends on your server. As a LW there isn't much to craft but the basic 640 gear so I'd suggest crafting those. This is what I would craft as a leatherworker.
Skinning is the best way to make gold with the gather professions, at least in my opinion. As with the other professions this depends on your server. Hardly anyone does the profession anymore so the leather is selling for around 3 each and the lower level leathers sell for more like 5 each and the lowest level leathers sell for around 1 each!
Herbalism is a great way to make money. With WoD introducing the herb garden in your garrison, most people ditched herbalism so now that the market is on a low stock of herbs, right now is a great time to head to some older zones and farm some low level herbs as they will sell for around 2 each or more!
Like herbalism, mining was also ditched by most people because of the garrison mine. So you can create profit from heading out to all the lower level zones and farming ore. In my opinion selling the ore raw makes more money then selling it smelted. Most ores will sell from 1 to 5 each.
This profession has never been a money maker and most gold makers just ignore it.
Cooking is also a great money maker. The reason for this is that like alchemy, raiders and pvpers will want food for the buffs. I recommend creating food then posting it on the AH on Tuesday or Thursday as these are the prime raid days. Most food can sell from 1 to 5 each.
Fishing is excellent parred with cooking. Also the fish sells for quite a bit. Fishing is way too time consuming and I can't sit still that long so I just ignore this profession. However fishing is a great way to make money if you have the patience. Most fish can be sold anywhere from 1 to 3 each.
Archaeology is, in my opinion is a terrible way to make gold. However there is already a guide here on Wowhead for that specific purpose. So here's the guide made by GeertJan.Huon Bronzebeards Guide to Archeology Gold.
The End of the Professions Section
This is the end of the profession section. As you can see, there are many things to sell and there is always profit. Based on my own experience and watching my servers AH has gotten me these results. On all professions this depends on the server as they're all different in what sells best and what doesn't. I play on a medium population server so on a high or low pop server this may work better worse. Just remember, in every main profession there is profit so try not to go bouncing around from profession to profession, which is what I used to do.