THE TL;DR ON CAST IRON
USING CAST IRON
Preheat it in the oven (always upside down, 325-375F), or on the stove top on medium. Have a little patience, a little planning. Move it around a bit (every few minutes) on the heat to keep the pan evenly hot. Medium (5-6 out of 10) is a high enough temperature for most things. Don't oil it until you're ready to cook; or the oil will smoke during preheating. Use a metal flipper and don't be afraid to scrap the pan. You can scrape it clean with some oil and a metal spatula while smoking hot if you like. VERY tough stuff, season included.
CLEANING CAST IRON
Clean and fully preheated = nonstick. Use nylon scrubbies and dish soap. Steel wool soap pads if it's really bad, but be prepared to add a fresh layer of season afterwards. Always hot water. It can't stay soapy and wet for any length of time, but it can GET soapy and wet perfectly fine. Dry and oil immediately tho, whilst still hot from the water. No temperature shocks, de-glazing a pan if fine, just don't dunk a smoking/glowing hot pan in cold water (you'll get cracks and/or warps).
MAINTAINING CAST IRON
Simply keep it oiled to prevent rust, just a thin layer will do, lard/shortening is best. After cleaning, oil it with lard on a paper towel or small rag; if any brown comes thru it's still dirty (or rusty), if black comes thru there is free iron coming thru the seasoning layer. I like to season mine fully so it's not messy like that, one coat usually seals a pan up great. It cooks fine with or without a seasoning (aka free radical polymerization layer, fyi).
SEASONING CAST IRON (whenever black is coming thru or you're just bored):
Oil like normal, make sure to get a good coat.
Rinse under hot water with a clean dishrag to get the oil layer super thin.
Dry thoroughly and make sure there are no 'dry' looking spots in the oil layer. Add just enough oil to make it not look dry. SUPER THIN or it will leave little shiny/sticky spots in the season.
Bake upside down at 475-525F; as high as your oven will go in normal mode, 60 mins or so.
Cool, oil, store/use.
Throw it on fire coals, or BBQ on max, or a oven on self clean for an hour or so. Heat until it's grey and the dirt flakes of like dust.
ALWAYS HEAT AND COOL IT EVENLY.
Soak in mild acid until it's gone and flakes off like dust. (Vinegar, Lemon juice, Cola drinks, etc.)
WARNINGS / TIPS
-Don't leave acidic foods in it long, picks up the taste and weakens/strips the seasoning, fine tho.
-No Heat Shocks.
-Keep it oiled.
-Clean soon after use, especially if there are/were watery or acidic things in it.
-Keep it oiled.
-To test a pan for microcracks hold it up with a stick/spoon and tap it with wood/knuckle... It should ring like a bell.
-Did I mention oil?
CAST IRON IS THE ONLY WAY.