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If you want to meet new people, you'll need to go where the people are. Most people find it easier to meet and make new friends in small group settings, so an interest group is often a better choice than a club or bar. Groups that allow you to engage with the same group of people regularly are more likely to result in friendships.  Pursue your own hobbies and interests. Depending on your interests, you could join a writing group, book club, bowling league (or similar adult sports league), gym, photography club, or cooking class. Getting involved in activities you can enjoy will help you meet people with similar interests. Get involved with your child's school by joining the PTA or becoming a chaperone on field trips. This can be a great way to meet other parents. Go to a house of worship. If you believe in a certain religion, start attending a church, synagogue, mosque, etc. If you already go to church, get involved with any religious study groups, volunteer activities, or social events the church sets up. No matter where you live, you're probably not the only adult interested in making new friends. Look for local groups and activities designed for the sole purpose of bringing strangers together. Choose activities and groups that you have an interest in. You will automatically have something in common with the other people.  This option works especially well for extroverts who don't mind large group settings. Organizations like this usually arrange a variety of activities, from cocktail mixtures to ski trips. If you don't know where to start looking, head online and check out daily deal services (Groupon, LivingSocial) or socializing services (Meetup.com). Ask yourself if there are any causes you feel especially compassionate about and look for volunteer opportunities that deal with those causes. You may make friends with the people you help or with some of the other volunteers. If you are shy, volunteering is good way to practice your social skills and talking to people that you do not know. Go to coworkers, relatives, or friends you already have and ask if they know of anyone you might get along with. Make it clear that you're only interested in meeting a platonic friend, not a romantic partner. Similarly, if someone suggests a friend to you without being asked, follow up and meet the person. A blind “friend date” may or may not be successful, but in each instance, you'll never know unless you try. Nowadays, few people really take the time to meet the people living around them. Go for a walk in your neighborhood and greet the people you pass. There might be someone you can get along with living closer than you realize. If you have a dog, be sure to take it with you on your walk. Most people love animals, and someone who wouldn't approach you when you're on your own might approach you if it means meeting a friendly furry companion. If you do not have a dog, volunteer to walk dogs from an animal shelter or rescue group. Make light conversation with the people around you as you go about your usual errands. Some people might act uncomfortable, but others may reciprocate your goodwill and start talking back. Think of every meeting as a chance to make a new acquaintance. For instance, talk to people in line at the grocery store or while standing at the gas pump. Going up to strangers is one of the most difficult ways to meet new people and can be difficult if you are shy or have difficulty starting random conversations. Too many people let the fact that they're alone stop them from enjoying all that their city has to offer. Force yourself out into the world without worrying about how it looks when you're by yourself. Visit places you enjoy. Go to a museum or head to a restaurant that serves your favorite cuisine, even if it's not an especially popular one. It'll be easier to run into people who have something in common with you. Few people will approach a stranger the first time they see him or her. If you become a familiar face at someone's favorite hangout, though, the other individual might become curious and eventually approach you. Choose a location with regular traffic yet small crowds. For example, head to a local coffee shop every Saturday at 11 AM or a low-key pub every Thursday evening at 7 PM. Repeat the process for several weeks to several months. No matter where you go, greet the people you pass or see with a smile. Your body language needs to convey friendliness. Others are much more likely to approach someone who seems friendly than someone who seems grumpy or distant. Crossing your arms and/or legs and looking down make you less approachable and like you do not want to be bothered. You might expect your new friends to be similar to you in terms of age, gender, and circumstance, but if you limit yourself to that one demographic, you may accidentally pass someone by who you'd get along with surprisingly well. Just because you are single does not mean all of your friends have to be single.  Build friendships based on common interests instead. For example, you might meet a neighbor 20 years older than you who happens to share your love for cooking and gardening, or you could make friends with someone 20 years younger than you who frequents the same museums and coffee shops.

Summary:
Attend an organized group or club. Utilize local social networks. Volunteer. Ask someone to set you up. Take a walk. Chat with strangers. Explore the city on your own. Be a regular at spots you like. Look approachable. Be open.