We all know that teenagers are going to withdraw into their shell and refuse to interact with anybody other than their own peers. Well, it may not be possible to avoid this completely but you certainly can reduce the intensity of this withdrawal by encouraging your child to be outgoing and gregarious from childhood.
If your child has a large number of friends and if he or she finds one reason or other to meet and interact with other people, it does not matter if he or she takes it slow for a few years at a stretch.
The best way to achieve this is to ensure your child has a wide social group from childhood. Make sure your child goes to the library, plays a sport, and tries to learn a new instrument along with studies and play. Of course, if you are going to ask your child to focus on so many aspects at once, you should be prepared for slight reduction in grades as well. As long as you focus on an all round developmental approach and do not equate good marks with good personality, you should have no problems in achieving your goal.
The idea is to encourage your child to reach that stage where he or she can take the leap into the big world of social contacts and networking without making too many mistakes. Mistakes will happen. That is a part of the learning process like knowing that addressing a lecturer as man or dude is simply not done.
Making sure that your child knows what to speak to whom and when to open the mouth and when to keep it shut is not something you can teach by theoretical lessons. Rather, keep pushing your child to interact with more and more people and that should do the trick.
You can only show the right direction. It is up to your child to explore and proceed ahead. The child may not work at your speed or may not work to your satisfaction. You should be prepared to let go beyond a certain level.