Tree snakes need a branch. Rocks, plants, and other furnishings are strictly optional. It is best to keep one snake in each cage, particularly if it's a snake eater like a kingsnake. But if snakes must be caged together, snakes of the same species are more likely to get along than snakes of different species. They never eat lettuce, carrots, bread, and similar items.
Individuals also show preferences.
Whenever possible, the snake's natural food should be offered. Most adult snakes should be fed every week or ten days, and younger, growing snakes should eat more often. A snake can go for weeks without food if necessary, but it does better on a medium sized meal once a week than a huge meal every three weeks. Hungry mice have eaten captive snakes, so a live rat or mouse shouldn't stay in the cage more than an hour if uneaten. However, snakes don't require live prey.