Unless you go with two gathering skills and no craft skills, you're usually spending money instead of making it, or at best breaking even. The only sometimes-exception to this is alchemy, since potions can go for a good amount of money on the market, however, it's usually still a break-even proposition, since even a low-level herb like briarthorn can go for 4-5 gold a stack, while the potions that are created with it go for less than that.
Given that most low-level items created through tradeskills are not bind on pickup, it's usually best to take two gathering skills and simply buy what you need from the AH or, if your gathering skills are complementary to your needs, eg skinning for a leather-wearing class, find someone that needs a skill-up and have them craft what you need with your mats.
To illustrate, I play on Detheroc. When I started my warlock there, I took herbalism and skinning. By level 60, I had enough for the epic riding skill + mount for my wife's character, a tailor/enchanter, and enough for the mats for my epic mount quest. At 64, I've almost about got the cost of one flying skill + mount covered, and should have the rest covered within 3 levels. At current rates, I expect to have maybe an extra thousand gold or so ready for spending on an epic flier by 70.
On the other hand, I have a level 61 skinner/leatherworker on Sentinels. While he was able to get his regular mount without much fuss, I'm basically going to have to go grind and grind in Winterspring for his epic mount, then grind some more at 70 for his flying mount. While he has had some nice gear on the way up, it's gear that I could have bought off of the AH, with the exception of one piece of dragonscale armor. If I had gone skinng/herbalism or skinning/mining with him, cash would have been no problem at all.
I'm in the same boat with mining/skinning as it creates a ridiculous amount of cash (new server and I didn't have to wait a second for my 40 or 60 mount!).
The second character on the server gets the same treatment, but I also treat myself to frequent, cheap, AH upgrades to speed the leveling a bit.
My intent is to level appropriate professions (based on class) at end-game for upgrades, but never for profit. So tailoring for some, blacksmithing (maybe) for others.
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