As simple as it sounds, you must be around people to meet people. But more important, my friend, you also need to interact with them, and in ways that are inviting and non-threatening. And finally, you need to take initiative in turning an acquaintance into a friend. This may seem very obvious, but believe it or not, communicating remains one of the biggest phobias among individuals. How many of us sit in front of the TV, alone, feeling lonely? How often do we go to social events only to look on from the outside? And how awkward do we feel as we're trying to extend an invitation of some sort? Probably the ideal way to meet others, my friend, is in the living of our own lives as we enjoy our hobbies and passions. But this requires making time for these activities (regardless of work demands) and knowing what they are. Team sports of any level can be a great way to meet others, or group interests such as dancing, meditation groups, book clubs, religious activities, choirs, hiking, etc. - which are all available in most cities. Opportunities for volunteering are plentiful, old friend, and this way of meeting others connects us to people with similar values while being meaningful in itself.
So, my friend, once we've gotten ourselves out there, or just decided to reach out to the people in our daily lives, how we do this is important. And little things can make a real difference. Having a candy bowl at your work area will always draw people over, providing a chance to talk. Making cookies or desserts for your colleagues is both emotionally and physically (well, maybe not) nurturing, and this attracts others. Just remembering birthdays and acknowledging special times (achievements, losses) lets others know you are thinking of them. Old friend, not all ways of connecting have to be extroverted.
More active approaches can also be simple, and maybe should be, at first. Rather than a direct invitation, a casual suggestion ("Since we both like movies, maybe we should go together sometime") can lower the risk level and give the other person an easy way to follow-up or let it go. Less "serious" or lengthy events are better at first, too: "coffee" versus lunch versus dinner. Offering help usually finds a receptive audience. At some point, my friend, everyone needs a ride, plants watered, something repaired, brawn for moving, assistance at work... (Of course, knowing others' interests and needs requires listening, a key feature in making friends). If you're an organizer, putting together a ski trip, hike, or just a night out is again a service, as much as it is doing something for yourself.
Once we've established a connection, how do we maintain and cultivate it? While it may sound cliché, the best way to make and keep a friend is to be a friend. My friend, the love you take is equal to the love you make. While your interests may not be the same as your friend's, think about what you want most from a friendship. At the days' end, human needs are basically the same: someone simply to be with; someone to trust; to depend on; to listen genuinely to us, caring about our feelings and perspectives; someone who'll tell us the hard things without meaning to hurt; who'll not let time or distance stop communication; who'll tolerate and forgive our failings; and who'll bring pleasure to our life by sharing the joy in theirs. If you do your best to be these things for your friends (like me for my friend) you will likely keep them. And through thick and thin the quality of your relationships will evolve and become richer.
Believe it or not, making friends is rather simple, but it takes intention, attention, courage, creativity, and love - and these things take work. However, the rewards are plentiful, and friends can make the intolerable tolerable. So, please, start planting some seeds; the harvest never ends.