Talk to people. Read newspaper announcements and check the library, university and the local town hall for a list of available activities. See what local businesses offer (like Running Room with their organized running clinics).
Are you sure you know what you are looking for?
What hobbies do you have? Singing, model building, mountain climbing?
Do you like old people/young people/sick people/church people/down and out people?
Find something stable - an outing club that's been around a few years, if hiking turns you on, for instance. A soup kitchen if that's your thing. Then join and stick with it for a couple of years. Get involved. Do more than the minimum.
Then, after a time you'll get known in that milieu. You'll become the 'prince of the principality' and the world is your oyster. Men will envy and respect you and women (young and old) will fawn over you.
Do your own thing to please yourself. Spend some time at it and things will sort themselves out. People are always unreliable - so don't count on them. If things fizzle out, just go onto the next thing. The journey is what is important.