dry burn before rinsing, otherwise whats the point?
if you dry burn after rinsing then all the stuff thats left behind from the rinsing will burn leaving deposits
if you dry burn before rinsing then everything will burn

and you can rinse off the solid residue
and when you dry burn then burn it proper, remove the coil from the atty to minimize chances of plastic melting (some of them have plastic real close to the coil like stardusts) and zap it from an external source for a good 5 mins at least, its clean when it stops making sound/smoke, all you should see is a quiet glowing coil. If you let it glow for 2 sec at a time for a few times like most people its completely pointless.