These things are more or less indestructable. I routinely put cold tap water into a hot skillet without ill effects. Once a skillet is well seasoned, no harm is done washing with soap and gentle scrubbing.
A new piece needs to be seasoned. I put some vegetable oil in it, and spread it around, "painting" the entire surface. Then just cook with it. Repeat this now and then. After a while you can forget all about this and just use it.
I essentially never wash mine. I scrape out any food debris, rinse with water and a brush if that seems necessary. I have been using my skillet for years and it has built up what seems to be an indestructable layer that food never sticks to.
If you have a new piece and feel an urge to scrub it to bare metal using detergent and some abrasive pad, you are working against yourself.
Some folks season their dutch ovens by coating them with oil (I use canola oil), then putting them in a 350 degree oven for an hour. I just tried this and it seemed to work well.
Tom's Dutch Oven Info / tom@mmto.org