Everyone wants a pet who is social, fun and friendly but that’s not the nature of every dog. Dog behaviour is driven by various factors, where they were fostered, where they were abandoned, what breed are they, did they socialise as a pup, their living conditions and so forth. Though there are ways to socialize a pet, which is usually best done while they are still puppies. Once their vaccines are complete, you can go through the following steps and see if it works.
Step 1: Ask a friend to visit you, make them ring the bell so your dog starts associating the doorbell with a visitor (this can also help them differentiate with someone who may break in). Sometimes it helps to make your dog sniff their belongings, a jacket or t-shirt beforehand so they have a sense of familiarity.
Step 2: Open the door with a smile and greet your friend warmly to create a sense of well-being and reassure your dog that this person is familiar and welcome.
Step 3: Ask your dog to come towards you and your friend. Maintain a non-threatening stance and speak in soft, gentle tones.
Step 4: Give your dog the command to meet your friend, you can use commands you may have taught your pet earlier like: say hello or shake hands or give paw.
Step 5: Ask your friend to come forward and accept the gesture. It is also good to keep a treat or reward so your dog understands that this is a ‘good boy/girl’ thing he/she did.
If this method works then by all means let then carry the interaction forward to a belly rub, a bit of play time or just letting your pet spend time with you and your friend.
Repeat this with all the new visitors in the house and in time your dog will start getting used to new people.