Get a crate big enough so your puppy or dog can stand up and turn around, but not any bigger.  Otherwise, it may use part of the crate as a bathroom rather than learning to control itself and wait until taken outside.
Make your dog's crate as inviting as possible.  Give it a treat when it goes into the crate, and stock it well with water and toys.
Keep the crate in rooms where people congregate so that the dog feels part of the family.  Stowing it in the basement or laundry room, away from the family, will cause the dog to feel isolated, says C.J. Bentley, a certified pet-dog trainer who works as an obedience instructor for the Michigan Humane Society.  "When you do let him out, he's insane.  So, he acts crazy, and then you throw him in the crate again," she says.  "It becomes a vicious cycle."
Use treats or a favorite toy to lure your dog into the crate and to reinforce the idea that the crate is a good place, not a puppy prison.  Consider feeding your dog in its crate to underscore the idea that the crate is its home.
On the first day you take your new puppy or dog home, introduce it to the crate for short stretches, 10 minutes or so, and eventually lengthen the time.  (Dogs often will bark when first introduced to a crate.)  Even when it becomes accustomed to longer periods in the crate, Bentley advises owners to continue using it when they're home so the dog doesn't associate it with abandonment.  Some dogs will become acclimated to a crate more quickly than others will.  For some, it can take days; for others, weeks.
Monitor your dog closely when you initially introduce the crate.  While most dogs will balk initially, some will become severely distressed and can seriously injure themselves if left alone.  If your dog wears ID tags on its collar, remove it when you confine the dog to the crate.
Limit the amount of time your adult dog spends in a crate to no more than eight hours.  Leave your puppy for no longer than three of four hours; just like their human counterparts, they lack the muscle strength to control their bladders for longer periods of time.
Never use the crate for punishment.  If you do, you will train your dog to dislike it rather than view it as a safe haven when it wants to relax.  And your dog won't want to use it to ride to the veterinarian's office, go on a family vacation, or sleep in at night.
If your dog shows signs of significant stress -- if its pupils become dilated or it begins salivating uncontrollably -- don't leave it alone in a crate.  Your dog may have separation anxiety and could seriously injure itself during a panic attack.  Seek the help of an animal behaviorist.

From the April 2003 Dog Fancy magazine

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