Hi Alan
I try to season my pots with animal fat, i don't get too concernerned with the outside usually just rub over the outside with whatever i wipe out of the inside after cooking a roast then maybe back on low heat to burn off any excess that said my pots don't look as pretty as some of the others on this site on the outside. I also live a long way from salty air so rust takes a while to get going, i always cook on coals so whatever i have tried on the outside seems to burn off after a few runs in the ash.
if you wash it out with detergent make sure its air dried properly (but not for too long) a week max) then wipe with a greasy/oily rag.
I also gently pre heat my oven before cooking anything that way any bugs are or other nasties have cooked out. and i get time for an extra beer
Mook