Well here’s what I Can help you with... I've been used to farming for those intermediate levels and I’ve come to a conclusion that for Alliance, it is Far easier to level up those early levels, However horde does win the Mining bucket with 1k Needles with its infinite Iron Deposits, as well as RedRidge Mountains guaranteed 3-4 in The Charred Vale. Now, If you happen to be Alliance, I have a pretty steady plan for your farming needs.
Step One: If you've got a Mount, knows the time to use it. Start your journey off in Westfall moving towards the Jangolode Mine, here you are guaranteed at least 1 if not 2 Tin nodes of which you can Mine. Your journey continues on to The Gold Quarry, where you will be guaranteed probably about 3, maybe even 4 Nodes. Now, as you continue moving, you'll notice you can continue to mine Copper to later sell on the Auction house. Now, I use the copper, and if my skill is still high enough to smelt Bronze, I’ll combine that with the Tin I find. Now, if your still discomforted, you can travel to the Deadmines and then mine the Tin that is outside the instance, and the few amounts that are within the instance. Guaranteed silver? No. But It is guaranteed to find you at least a few Tin Nodes that are easy as pie to farm. By the time you finish one circuit, the ones in Jangolode should have respawned.
Now... If your horde. My memory Is foggy so I'm unable to think of how to level that. I'd suggest walking about in The Barrens for Tin... that should be plentiful in that Area.
Good Luck with your Mining
-DuctTapeSavior