Learning to think in the same terms as your ferret is as simple as one word: UNDER. If there's a way, he'll find it!
Ferrets are attracted to anything that resembles a tunnel, probably because this represents two things to ferret instincts: safety and food. They are predators who are small enough to be prey to most other animals. So a ferret is a mix of tiny ferocity and caution.
Being well-fed (we hope!) and domesticated, most of the ferret's ferocity comes out as play. He will mock-attack anything that moves, from your hand/foot to the bedsheet you're spreading. Then he'll hop up and down, twisting his body one way and the other, and making soft "chirping" noises at you -- the Ferret Wardance.
"Discipline" is a foreign word to a ferret; if you're into it, get a dog. Ferrets do not respond well to it. But you can't just give the little monsters free-rein, or your house will end up trashed.
Actually, with that said, I DO discipline, but primarily by voice. Use a sharp tone, and be willing to go to where the ferret is -- otherwise he'll ignore you. When I do have to remove them from whatever they're doing, I do it gently. Remember, he was just exploring and amusing himself -- he has no idea why you're yelling at him.
About the only act that calls for real discipline is biting, and I'm not going to get into that here.
With that said, here are some thoughts on how to proceed.
- First, get a comfortable cage, and keep your ferret(s) there when you are not able to supervise them. They don't mind -- it's their home.
- If they're making a noise with something, and you don't know what they're doing, CHECK!! (Unlike children, they never figure this one out.)
- If the ferret is getting into something you don't want him to have, move it out of reach. STORE it out of reach -- ferrets have long memories.
- Block access to places you can't reach, preferably BEFORE the ferret discovers them. (See Ferret-proofing your home.) Keep doors to off-limits areas closed at all times. I keep a sheet of plexiglas to block my ferrets downstairs when I'm downstairs. That way I don't have to run upstairs constantly to check on them.
- Keep all tempting items (like houseplants) well out of reach at all times. Don't teach the ferret "tricks" that you will later regret. Don't tease them with something, then put it out of reach.
- If they poop somewhere consistently, put a litter box there. (Give it up -- they train you.) If that's impossible, there are a couple of other tricks, like making that spot resemble a "sleep area" with ferret-smelling towels or sheets, or a "play area" with tubes to crawl through -- ferrets won't poop in either. Making dead-end tunnels into non-dead-ends often helps, too.
- If they're doing something annoying, like scratching, distract them. If they do it again, distract them again. Usually they're just bored and think you should be entertaining them. If you can't, put them into their cage for a "time-out" until you can play with them.
- Most important, be inventive! There's no way to cover every problem and solution I've dealt with, but the more innovative solutions seem to work best. A bored ferret is a destructive ferret, so try putting yourself in your ferret's *paws* before condemning him.