Teach 'touch' or targetting:
Teaching a targetting command can help your dog to learn to settle on a specific location in the presence of new people/situations. Teaching touch can help to increase the confidence of the more timid dogs.
Targetting - essentially choosing a 'spot', could be their bed and leading the dog over to it, saying your word for the target 'bed' for example and building up your dog's association of the target. Reward for the behaviour you want. This needs to be repeated over and over, and increasing the distance away from the target until your dog can go to their target when asked. If your dog is beginning to display uncomfortable body language in a certain situation you can ask them to go to their target to settle.
Touch - getting your dog to touch you with a part of their body. Usually their nose/snout. You can either begin training by catching the desired behaviour as they do it. For example, if you reach your hand toward the dog and they touch it with their nose, say 'touch' and reward. You can also hold a treat in your hand and when the dog sniffs and touches your hand with their nose, praise and treat. You can build this up until the dog is confidently coming forth and touching your hand - you will find that the more you do it the less apprehensive the dog will become. It can help the very nervous dogs who are scared of touch to learn that human touch = rewards.