I believe I needed 230 in smithing for mithril, and 250 for thorium. South Darkshire does have some iron veins that are easy for a level 30 or so to get, regardless of the mobs nearby.
One of the bigger issues that a gatherer/crafter runs into IMHO, is focusing on the gathering or crafting rather than just playing/leveling. My miner/blacksmith hit level 40, and I ran over to the artisan trainer for quests, and quickly found I was too low on my skill, so I had to gather ore. I focused on that, and found it frustrating as well, trying to find regular veins. I finally realised that I wasn't going to live o die on when I became a certain level or crafting skill, and to just continue playing. I gather ore regularly while doing quests and killing mobs, and things are going just fine. :)
Since you need to be a certain level to reach various levels of crafting anyway, this is an obvious choice. Focusing on one area to the exclusion of others only hurts you down the road. Such a dueling all the time before you have a level 60, but that's just me.