I can't speak on the subject of more common household pans and whatnot, but I do have quite a bit of experience with cast iron dutch ovens. It's a good idea to not only season these puppies when new, but at least once a year (at the beginning of the camping season is always a good time), or after any extended storage period. This will keep them in good form.
As far as cleaning, here's my method. Using a small amount of clean water and a soft plastic brillo pad, scrub any remaing food particles off the surface. Dump out the water, and voila, the food comes out with it. Repeat if necessary.
Once any surface residue is gone, take a paper towel and some Crisco or a similar "shortening" product, and give the inside of the "dutch" a light coating.