If you are a low level toon and want 200 gold, go and learn Skinning + one of Mining or Herbalism. Mining is marginally better for mellee toons, and herbalism is slightly better for ranged toons.
Regardless of what skills you get, spend an hour gathering in your starting areas and post your stuff in the auction house, for the 'mid range' of what you see items sell for. Yes copper, silverleaf and light leather + leather scraps really do sell.
If you are a higher level toon, and are struggling with gold, take at least one gathering profession and gather it till you get to 450. Combine gathering with dailies. Consider gathering in Outlands. 500g/hour should be yours for the taking.
Get a 'bank alt' (possibly a level 1 toon), and put it at an auction house, and mail all gathered stuff to him. It saves time continuously running to the Auction house.
Keep your gathering skill for when Cataclysm hits. Gathering will make a fortune for the first part of Cataclysm. (My guess : 800g/stack of anything cataclysm for the first few days.)