1. First you should decide whether you want a game or an educational program.
2. If you choose a game then consider the content of the game. Violent games may encourage violent behavior. Games with moral content may encourage moral behavior. Keep in mind that the type of game may effect your child' behavior.
3. Consider the level of the game whether it is designed for your child's age group. Remember to consider if your child is smarter then most children you may want a game designed for an older age group so he does not get bored with the game. If your child is not learning quickly and his skills are generally lower then his age group you may consider programs designed for kids of a lower age group.
4. Consider whether the game contains characters or topics of interest to your particular child. For example if your child likes the character Dora you may want to buy games that have Dora included!
5. Visibility of the game may be important. If your child is color blind a game which uses a lot of colors may not be helpful to him. If the game has a lot of writing and subtitles and your child cannot yet read it may not be good for him. Generally, children that cannot yet read may respond with more elaborate and colorful games then a child that can read. Similarly, if the child cannot hear well then more visual pictures in the program may be more effective for him.
6. If you choose an educational game or other games it is important to check whether the authors describe research that confirms that the child will learn for the game. For example, there is a game called "Head Sprout"(recently purchased by another company) that does have research that confirms that the children do learn to read from using the program. Games that have been scientifically validated to use psychological principles that are effective are the games to choose for your child!
7. Always consider the child's preferences before making a final decision discuss the options or even show him the games to get his input and assure that he will like the game.
8. Try to select games that include some reinforcer after correct performance if possible within the game!
Generally, the most important factor is to choose games that are validated to be effective. Secondly, to choose games that match your child's individual needs.