even before i took up mining, i saw tons of these veins which some miners come here and post about not finding.
if you dont find it, you're just not in the right area yet. eg, dont go to sentinal hill and say, no tin ores here. instead. go up to the mountains, check the caves, before you give up on finding tin ore.
and speaking of westfall, there are 2 caves which spawn several tin ore veins, which you can do solo without having to get a VC group to go into deadmines instance.
now mining is a little different from herbalism at the same zone/level when you consider caves. you actually waste more time trying to kill mobs in the caves to get to the vein, not to mention being stuck in the cave when they respawn. so either look for veins that are out in the open/in the mountainside, or wait a few levels to where you can either easily kill the cave mobs or simply walk by most of them.
otherwise you spend so much time trying to get a few ore to increase a tradeskill instead of just levelling up to where getting that same ore is a little easier, not to mention people may reach level cap so fast that they then end up spending several levels without making anything.