The No. 1 Command: Sit
Sit is by far the most important behavior for a dog to know before visiting other people, and is the exact opposite of nearly every obnoxious behavior the dog may exhibit during your stay, including jumping on people or furniture, wandering away, or knocking things over, Westcott said. You dog should also have an understanding of how to control his mouth and voice, with a “sit” command helping to curb any inappropriate chewing, biting, and barking.
To teach your dog to hold a sitting position, ask for the “sit” and withhold your reward (usually a small treat) for a few seconds after the dog has complied, Westcott said. After having repeat success with a few seconds in the sit position, begin withholding the reward for longer intervals of time. Continue this pattern of having your dog wait for the reward until your dog understands that “sit” means “sit down,” as well as “sit and calm down.”
As your dog gets better at sitting and staying on command, stop using a treat every time for the reward and gradually replace the treat with affectionate petting and words of praise. Eventually, and with practice, your dog will sit without expecting any reward other than your approval. And that's a dog you can take anywhere!