I have been developing my social skills for past 2-5 years and am now a more pleasant person, talk better, can speak up for myself better, and can make small talk to strangers sort of. I have used these in my efforts to improve my social skills and find more friends:

job - i talked to customers and coworkers at work and gotten better at talking
a friend - any friend you spend time with and talk with helps
finding public events online and going to them - going to a free movie screening with some activists, a show or a punk rock concert, a pick up game of frisbee/basketball/volleyball/etc.
take a dance class and go social dancing even if you suck and can't dance shit still improves your social skills a lot
dress up and try clothes you would never wear that are totally not your style but still match and fit you well
group psychotherapy
support groups of any kind
stake a beginner acting class for adults or improv class
meet up groups like where you act or dance or play games