Go to sleep and wake up on a regular schedule every day, eat a good breakfast, and start every day with a shower and a cup of coffee.
Socializing is an activity that demands more from your brain than most anything else, and a quick wit only comes to someone who's well-rested. When you can think more quickly, comedy comes easy and is more natural, which will establish a personality to attract other people. People who fit in really well socially are generally happy.
Also, rest will help stabilize mood swings and keep you out of those really, really deep feelings of dread and melancholy. Eliminating as much unhealthy food from your diet (especially sugary stuff like soda, candy, etc.) as possible will make it easier to maintain a positive, confident mindset that others will be attracted to.