This article is from the Dog Crating FAQ, by Cindy Tittle Moore with numerous contributions by others.
* Do think of the crate as a good thing. In time, your dog will too.
* Do let the dog out often enough so that it is never forced to soil
* Do let the dog out if it whines because it needs to eliminate. If
you know it doesn't have to eliminate, correct it for whining or
* Do clean out the crate regularly, especially if you've put in a
floor and you have flea problems.
* Don't punish the dog if it soils the crate. It is miserable enough
and probably had to.
* Don't use the crate as a punishment.
* Don't leave the dog in the crate for a long time after letting it
eat and drink a lot. (because the dog will be uncomfortable and
may have to eliminate in the crate.)
* Don't leave the dog in the crate too much. Dogs sleep and rest a
lot, but not all the time. They need play time and exercise. When
you are at home, they should not be in the crate (except at night
when they are still very young puppies). If necessary, put a leash
on your pup and tie it around your waist while you're at home.
* Don't check to see if your dog is trustworthy in the house
(unsupervised, outside of the crate) by letting the dog out of the
crate for a long time. Start with very short periods and work your
way up to longer periods.
* Don't ever let the dog grow unaccustomed to the crate. An
occasional stint even for the best behaved dog will make traveling
and special situations that require crating easier.
* Don't put pillows or blankets in the crate without a good reason.
Most dogs like it cooler than their human companions and prefer to
stretch out on a hard, cool surface. Besides providing a place to
urinate on, some dogs will simply destroy them. A rubber mat or a
piece of peg-board cut to the right size might be a good
compromise (be sure to clean under any floor covering frequently).