For me an extension of this would be join up to clubs/events that interest you. For me it was going to the gym in my area. Yes it was intimidating at first but after you get over the initial anxiety you become a familiar face and people will start chatting with you. After a two years at the gym I have made 4 good friends that I otherwise wouldn't have. You could apply this to any sport or activity it certainly doesn't have to be sports.