The following is a list of guidelines to keep in mind when designing your inheritance relationships.
Always make a subclass capable of doing everything a super class can do
Ensure that a subclass holds all information that the super class holds
Add attributes and behavior to the subclass to define behavior that is more specialized than what is found in the super class
Move common characteristics to the super classes
Allow different subclasses of the same super class to do the same thing, but differently
