Your ferret will indicate when it wants to be picked up by holding onto your leg or by grabbing your wrist when you extend your hand.Ferrets should be picked up from behind using two hands, one supporting the chest and the other cradling the hips. A ferret should never be grabbed at or be picked up by its tail. The ferret may become nervous and nip if you do.
Ferrets by nature will nip for fun, attention or simply to say "I'm the boss." Nipping could quite possibly continue beyond their terrible twos. Ferrets have tough skin and enjoy rough-and-tumble play with each other, which includes playful nipping. They will need to learn they cannot be as rough with you.
A ferret should never be hit for nipping because that will make it nervous and it may bite out of fear. In the event that a ferret nips and hangs on, grasp it by the scruff of the neck, remove the ferret, then say, "No!" loudly. You may have to repeat this several times until the ferret learns who is boss. Just know that saying "no" to a ferret at first seems to be interpreted as "do it again." It is up to you to teach it acceptable behavior.
The only times ferrets may bite are when they are malnourished, terrified, neglected or abused, ill or in pain. Any animal would do the same.