Social skills really matter. When someone invites you to a party, go. When someone asks you a question, answer. A club you're interested in? Join it. If there is an opportunity to do something great, even if it means stepping out of your comfort zone, do it.
There have been a lot of missed opportunities in my life, I regret not taking those chances. Opportunities rarely come back after they've gone.
Always, always, get a chance to know people. Talk. Joke around. Laugh. Make friends. Never let your insecurity or fear get the best of you. Otherwise, it will start to control you.