Housing
Corn snakes will eat other snakes: they should ALWAYS be housed alone.
A baby corn snake should be kept in a 10-gallon aquarium; adults require the space of a long 20-gallon+ aquarium. Newspaper, paper towels, and Astro-turf are all suitable materials to use on the bottom of the enclosure (gravel, cedar shavings, and bark should be avoided).
The enclosure should have several hiding spots, at least one on both ends. Hiding spots can be made of anything as long as the snake can completely fit inside and hide itself from view.
A sturdy bowl of clean water, large enough for the snake to soak in, should be available at all times. The bowl should be in the cool side of the enclosure so the snake can always get a cool drink of water.
Snakes are escape artists - a secure screen lid is a must.
Simple routine cage cleanings with mild soap and water should be done at least weekly. Both cage and substrate should be dry after cleanings. Between complete cage cleanings, all fecal material and areas of wet substrate should be removed as quickly as possible.
The cage should be disinfected once or twice a month. Commercially available disinfectants, such as Rocal and Nolvasan, are excellent. After sterilizing, be sure to rise well and let dry.
Water bowls should be changed on a regular basis to prevent the growth of parasites or bacteria. Chaing the water twice weekly should be sufficient and disinfecting the water bowls twice monthly will eliminate the potential for problems. Of course, if your snake defecates in its water, the bowl should be removed, cleaned, and refilled right away.
Temperatures
The enclosure needs a warm end and a cool end so that the snake can regulate its body temperature. Temperatures should range from 70-75 degrees Fahrenheit on the cool end of the enclosure to 82-86 degrees Fahrenheit on the warm end. You can accomplish this by placing a reptile heat lamp on top of the screen cage-top and using an undertank heating pad (both are available at your local pet store). When placing the heat lamp, make sure it is not close enough to burn your snake.
DIET
Corn snakes should be fed an appropriately sized mouse once a week. A good rule of thumb is to feed the snake a food item that is the same, or close to, the snake's diameter. Pre-killed or stunned mice are best because live mice can fatally injure a snake. Frozen mice can be thawed by placing them in a plastic bag floating in warm water. They should be fed to the snake using long tongs.
It is important to keep the enclosure temperature steady before and after feeding your snake: if a snake is cooled and kept cool after it has fed, putrefaction in the gut of the snake can occur. This can result in regurgitation of the prey, or in extreme cases, in the death of the snake. The snake shouldn't be handled for at least 2 days after it has fed.
HEALTH
Any newly acquired specimens should be checked for parasites, strength, alertness, and symptoms of respiratory distress. All specimens should have a routine fecal exam done by a qualified reptile veterinarian. When your snake first defecates, collect the feces in a clean plastic bag, seal it, label it with the date, and take it and your snake to a vet who is experienced with reptiles and have the sample tested for worms.
RECOMMENDED READING
The Corn Snake Manual, by Bill and Kathy Love