At nearly 3 years old, your little one is at the age when they need to start socializing as they would soon enter pre-school. If you teach your kid positive ways of social behaviour, soon he will develop a confident nature.
What you need to know
Confidence cannot be taught verbally - it requires examples and practical situations through which the child can learn a lesson. You can start with basic steps like asking the child to introduce themselves in front of the family. If the little one hesitates then encourage them with a kiss or a hug. Never stop the child while they are exploring new things. If you restrict them then it might hamper their creativity and inquisitiveness.
Make the child indulge in various activities such as sports, drawing, music or dance. Such activities are very helpful in confidence grooming. Take the child for a walk or to the playground where they can interact with children of their age. Let them learn to get comfortable with people so that they can easily make friends when they join school. It requires great confidence to do any task and it is your responsibility to make your kid develop this feeling.