You might just adopted or bought a dog, or it is just a visiting dog and the dog/puppy might be timid and display avoidance and fear attitude. You will have to overcome your dog shyness, but you will have to spend some time and effort into it.
Here's a few steps that you might want to try out :-

• Present unthreatening appearance
• Get help from other visitors

Dogs are just like babies, who can be afraid of figure looming over them. The towering height of a human can be frightening to dogs and puppies. Crouching down to eye level of a dog can lessen their fear towards you, and you may try to attract them with treats, perhaps the ones with scent. Wait for the dog to get curious to come to you. Do not make any sudden movements, or noises that will caused him more fear .

You may want to get a friendly, active dog to socialize with your shy and fearful dog. However, be sure that the other dog is not aggressive, which might hurt your dog instead. If finally he is willing to come out from his shell, don't scare him off by your excitement and lavish praise, which should come later. Let your dog or puppy has his time to look over you, and encourage him by holding out your hand for him to smell.