I found a bit of iron, but it's really difficult to spot. Now I need Corrundum and I can't find any...

its very hard to find.

the easiest way to advance smithing is to BUY a bunch of iron ingots and make a bunch of iron daggers. it'll go up very very fast.

look for the hammer and pick icons while roaming around and check the orc settlements...the one i ran into had an ebony mine loaded with iron and ebony.