We only use cast iron cookware, nothing beats it. However I am in constant battle with hubby, as he keeps washing and scrubbing my frying pan...I finally get it with a good season and he scrubs it off! grrr
Definitly don't use olive oil...tried it once and it was NO good. I use lard now, it works very well.
When I was growing up, my family would leave the bacon grease in it after breakfast to harden and it stayed in there until the next time the pan was used, just scraped out beforehand. That pan was very well seasoned!
I've learned that it is important to let the pan warm up, and to not use high heat (I rarely go past 5). Again hubby has a habit of putting it on high...grrr
I have accidently forgotten the pan on a burner to dry...it smells terribly when the iron overheats, and it burns the nose.
You may have to burn off the residue on your pan, leave it in a fire till it cools. Then start over with the seasoning.
I have also read that the newly made cast iron pans are not made well - the surface should be smooth but the new ones are rough. It takes longer to get the surface smooth (it is the bits of food/grease/etc that fill in the pits to make it smooth so you don't want to over scrape when cleaning).