I get compliments about how polite my toddler is. At two-and-a-half years old, she greets adults by name; she says please, thank you, and you're welcome when it's appropriate (most of the time); and she is very complimentary herself ("I like yours shoes. They're so pretty.")
It isn't by accident that she is this way. This is behavior that I actively tried to instill in her from the time she was born. I have seen conflicting advice about teaching keeds to be polite so I think it might be useful for others to know what I do.
1. Model Good Behavior
I think this is a key step in teaching kids how to do anything. We say please and thank you to the toddler. When I ask her to do something, I say please. When she complies, I thank her. It's not difficult. I started this when she was a newborn so that I would get into the habit. ("Don't roll off the changing table, please. Thank you.") I read in a book that you should only model behavior and never tell your kid to say please and thank you since they will naturally pick it up, but I don't agree. Kids need prompts.
I compliment her every day and I compliment other people in front of her. I tell her she's funny, or I say that her hair looks cute, or I like the picture she colored. She says thank you, and she copies that behavior with others.
2. Remind, but Don't Demand
I read in a book that you should not force your tiny toddler to say please and thank you. You should remind them to do so and let it go. If my toddler forgets to ask for something in a nice way, or to say please, or thank you, I remind her, but I don't force her to do it right then. Using this method, her use of please and thank you gradually increased on it's own.
This was another thing I started when she was a newborn. It was a little ridiculous at first because I would be holding my tiny baby who couldn't even hold her own head up and I would say, "Say hi to Aunt Marie," and then I would say it for her, "Hi, Aunt Marie." But, at her two-and-a-half-year check-up, she greeted her doctor with, "Hi, Dr. Altmann," when the doctor walked in the room so, as ridiculous as it seemed then, it has paid off.
When I started this post, I thought there was more to it, but as I got into, I realized it really has been as simple as that.