Good Manners for Children as a Basis for Good Behavior

Children can be very difficult to be around when they behave in a rude and selfish way. This is equally true of adults, too, by the way, but if you are the parent or grandparent of a child, you have a hope of teaching your child to be different. The younger you begin the teaching, the easier it will be for your child to have good manners as a matter of course.
The basis of good manners is kindness. If you raise your children to have empathy towards others, they will be less likely to choose actions that hurt others. Some people call this the Golden Rule. It is easier to explain it to your child in situations they can understand, such as sharing toys or cookies with a friend. When something happens where they have acted selfishly, remind them that they would not want someone to treat them the same way. Ask them how they think the other person feels when treated that way. 
Expose your children to the best role models you can find in the way you want your children to act. This may mean limiting your child to some negative role models on television and in movies. It may be acceptable for the villains to be nasty, but when the heroes act much the same, it is probably time to turn off the show. When young a child's biggest role models will be their parents, grandparents and babysitters. A child should be hearing "please," "thank you" and "excuse me" quite frequently before they are old enough to say the words themselves. If you are saying "please" and "thank you" to your baby or toddler all the time, they will automatically begin saying these words as soon as they can talk. The opposite is true of rude words or curse words you do not want your children to be saying. You should be trying to prevent your children from hearing these words. At least they should not be hearing them from you.
Table manners can be a little more difficult to teach a child since a lot of slack needs to be extended to young eaters who have trouble getting the food in their mouths. Gentle and frequent reminders will be required as children become old enough to adopt more gracious behaviors. Again, the parents will be the best models of appropriate topics of conversation during meals and how to handle the food neatly. Parents of children must always be unlearning their own bad habits, if they realize, for example, that they themselves have been chewing with their mouth open or slouching at the table.
The most important thing adults around a child can do, and especially the parents, is to set a good example. If good manners are second nature to you, even among members of your immediate family, then your children will thrive in the environment you are raising them in. Whether you have good manners yourself or not, your children will probably grow up sounding and acting just like you.