My clean-up routine is:
Remove and brush my grates then wipe them with paper-towels.
Take the foil of the firebox while it is still in the smoker, leaving foil in smoker.
Remove fire box, dump ash, scrub bottom with grill brush and wipe with paper towel.
Fold foil covering bottom of smoker onto its self to prevent any drips, remove and throw away.
Wipe bottom of smoker with paper towels.
Remove drip pan and, discard contents, wipe with paper towels, clean in dishwasher.
*However on the occasion that what I smoked did not produce a large amount of drippings, all I do is dump the ash from the firebox and wash the drip pan.