I started to play on Lordaeron's server two weeks ago, now I'm level 20 and I wanted to start farming copper and tin, I found some guides on the internet but none of them could really help me, some of them says that in Undercity or Durotar you cand find it, but I searched in that places for some hours and I can't find anything
They have updated or fked up ores spawning position, so that might be the cause of it.
I have noticed yesterday that some ores disappear when you get close to them, like they are phased, and old ore spawning points are no longer spawning them.
Tirisfal Glades is definitely the best location for Copper that I have found, even as an Alliance player. There is basically no copper in any other starting area I have come across, other than the occasional node.
Tin seems to spawn in more zones, so I found it easier to farm than copper as I was lvling.
Get GatherMate2 and Routes they are addons that will solve all your gathering needs. All the routes from retail and molten work the same on warmane. I've used the same routes for 11 years no issues. It is a simple google for any 1-450 mining route for horde or alliance.
Mining nodes (and herb nodes aswell) were modified recently. I would recommend to join a big guild, get Gatherer, wait for others to send their gathers and start checking where nodes spawn, so you go and mine there.