Seasoning is VERY easy. Line the bottom of the oven with foil or a cookie sheet in case oil drips (though I’ve never had any drips.) I was always told to preheat your oven to 350 degrees, which I have done, but now I see sources say up to 450 degrees. (That’s what I love about cast iron, it’s pretty resilient as long as you don’t warp or crack it.) Apply a thin coat of cooking oil to your cast iron (I use avocado oil.) Make sure your oil layer is thin, you shouldn’t really be able to feel it, though the iron will be a bit shiny.
The first time I seasoned, the kids and I slathered on nice thick coats of oil all over our first pizza pan and the pan came out of the oven all sticky and gunky. I thought I had to scrub off the goop that was baked on. I ended up using soap to get the baked oil off. Now I’d probably just keep cooking until the gunk went away, but back then I didn’t know how resilient cast iron is.
When seasoning, put the oil on the inside, outside, and handles. Put the cast iron in the oven upside down to allow for dripping. Bake for an hour then turn off the oven and let the cast iron sit until it is to cool to touch.
That’s it. That’s all that seasoning is—applying oil and baking. I try to repeat about 3 times. (Though I seasoned my 9 quart dutch oven 12 times. Since it is just for broth I was afraid all that water would cause the pot to rust. Twelve coats of seasoning worked wonderfully.)
And here’s the disclaimer part. As I worked on this project I could rationalize buying all the cast iron cookware I wanted so I could experiment with various pans for different recipes. As time went on I got kind of lazy about seasoning before I use the new items. Now I put a little oil in the pan, heat it a bit while I’m prepping my food, and I call it seasoned. I wouldn’t do that for a pot meant only for broth, but for general cooking it’s been fine. Perhaps if I didn’t live in the arid desert things might be a bit different, but here this works just fine.
If you want to see how to clean cast-iron cookware, including how to get the rust out of the little dutch oven, see this page.