Dubbin applied when they've been wiped clean, and only when needed (maybe twice or three times a year for boots that have been regularly exposed to the elements). Apply it all over, especially to the welt and any seams on the boot, after having used a toothbrush and water to get any dirt out of those areas.
You can get a shine out of any leather, just some require more effort than others. The only real way to shine waxy leather is to properly bull it with a decent amount of elbow grease. Heavily bulled boots will need stripping down from time to time so that you can feed the leather.