Without too much work it's not difficult keeping up with enough for training. I rolled an alliance toon on another server for kicks (I usually play horde) and I had about 8g by the time I was level 12 just by doing these things:
  • Make sure to loot everything.
  • Vendor grays.
  • If you can't use any of your quest rewards, select the one that will vendor for the most amount (usually plate and weapons). There are addons that will tell you the exact amount in your tooltip.
  • Auction off greens (or DE them and AH the mats). Greens will go for at least 2-3g and higher, depending on the level and also what they would DE into. Charge more for leather with agility and AP, cloth with int, spellpower and stam, mail with str, agi, plate with str and dodge, etc. Auction off greens even with worthless stats, because there are people out there who make money by DEing them and reselling the mats for more!
  • AH any whites you come across as well.
  • Pick up skinning, AH them.
  • Get Herbalism. AH the herbs. Do not sell the herbs too cheaply - inscriptionists will pay a good amount to make their glyphs.
  • Buy your faction's pets and resell them on the neutral AH. You can often buy a non-combat pet for 50silver and resell it on the neutral AH for loads more. Same goes for recipes.
  • Don't buy stuff you don't really need.
For the OP - I'd suggest picking up two gathering skills and going back to the old world to catch up. I'd personally go with skinning and herbalism because they don't share nodes on the map. Herbing is really easy, especially in the newer areas (like the bloodelf and draeni zones). Skinning should be easy as well since there should be other people doing their quests and leaving dead mobs behind. If needed you could always one-shot your own. If you're really nice you can offer to group up with some lowbies to help them if they let you skin everything. Then just AH everything.

Get auctioneer!