Some awesome galaxy-brain answers in here. Before you cook with the cast iron skillet for the first time, coat in oil and pop it in the oven on the self-clean setting (or just the hottest it will go) for like an hour. Really bake that veggie oil or whatever cooking oil you used in there. Then let it cool and rub just enough fresh oil in to make it shiny. You can repeat this process a zillion times and it will make your cast-iron better, but you don't really have to repeat it if you don't want. When you cook with it, use a small amount of oil as you would with any other skillet. (Some people don't do this, but until your skillet has a few years' use on it at least, it's probably gonna stick.) After you're done cooking, let the grease cool down, then wipe as much of it out/off as you can with paper towels and throw it away. If you're the type of guy who collects bacon grease, well, pour it into your can while it's hot, I guess (I don't). Then get the sink tap running as hot as it gets and start rinsing. I never use soap; it ruins the non-stick goodness. Scrub it with a specialized chain-mail thingie like this: https://www.lehmans.com/product/chain-mail-scrubber That will get any grime off. Once it's clean, dry it off with a towel and then rub in a little oil to make it shiny. Some people pop it in the oven on high again for a while, but I don't because I'm lazy. Cast iron doesn't have a chemical coating, and it's never going to look perfectly smooth or perfect in any way, really. If it's jet black and shiny, you're probably doing ok. I promise you do not need soap to clean it any more than you need soap to clean your grill grates. Rule of thumb: If you wouldn't do it to your grill, don't do it to your cast iron. Much like your grill grates, cast iron cooks best when it's screaming hot. I like to sear stuff on it for a minute or so per side at 1,000 degrees or whatever and then pop the skillet in the oven for four minutes or so to finish the steak or whatever. It's perfect. TL;DR: Hot water and scrubbing. That's it.
I love them for backpacking too. But seriously, agree with this for searing and the stove-to-oven combo. If I'm not grilling, I like to sear steak in the iron skillet and then move it to the low-ish temp over, with a thermometer, to get perfect medium rare. I've also been cooking a mean buttermilk-brined chicken in a skillet in the oven.
I have no trouble using a little soap on mine if they are extra dirty/greasy. I never worry about losing the seasoning........but then again, I use mine pretty much every day. Aluminum and copper are MUCH better for even heat distribution, but there's just something about my cast iron. Also, I like having various "zones" of heat. I can sear one palliard chicken breast in the hottest part of the middle, then move it to the side while I start the next breast. Same thing for pan sausage in the morning. Granted, I'm talking about a fairly large skillet. Also......there's something about fried chicken done in a half inch of oil in a cast iron skillet vs. deep frying. They are also a good substitute for wok cooking.
Yep, the only things I don't like to cook in mine are scrambled eggs/omelettes and really acidic stuff like tomato sauces (bad for the layer of seasoning).
Pour off excess grease. Pour in large grain salt like kosher and scrub with rough side of non-soapy sponge. Wipe with thin coat of vegetable oil or bacon grease and heat again till it just starts to smoke. Remove and store.
