Nose flicking is instinctive, but the ferret will learn to associate your hand with pain and you want to avoid that. Alternatives include, try using a signal he already understands such as a high pitched yelp, give him time out in a cage and ignore him for a few minutes. Most ferrets hate the taste of this, and will soon learn that you taste very bad. Scruffing and shaking gently while you hiss at him will mimic the mother and tell the ferret that you are boss and you don't like what he did. Saying NO very loudly while doing this will also teach the ferret to associate NO with being in trouble.
Frequent bathing can tend to dry out a ferrets skin.
In addition, to compensate, the ferret will secrete oils that contribute to his smell. We recommend only bathing a ferret once every four to six months. Ears should be checked at the vets for ear mites, and cleaned once a month. Your vet can tell you how to safely clean them. Nails should be trimmed at least once every other week.