If you want a lover there's Tinder, clubs, etc. If you want business connections, there's Meetup, Linkedin, networking events, etc. What do you do if you just want to find people of any gender to become friends with?
Assuming you have a day job (ie, an office where you'll meet and socialize with people even if it's limited):<p>Invite them out, accept their invitations. You don't have to become friends. Get to know their friends and friends' friends. You'll click with someone, start inviting them out to things or over and accept their invites.<p>Create opportunities for people to be social with you. Go to a bar or restaurant that hosts trivia, attend regularly. Chat with the other teams, invite people you meet to join you.<p>If that doesn't interest you, find other activities. Go to movies (with dinner before/after since movies aren't really social), host a movie night, board games, set up a hiking group, or find one to join.<p>One thing I've learned, I have to take the initiative to invite people. And I can't turn down invitations when I've first met people. If I meet someone and sort of hit it off, but turn down their invites to activities, I'm not going to be invited to join them again (or I'm less likely to be). But when I invite people, I'm generous about re-inviting people who turn me down. I throw out invites to 10-30 people for events, and I may only get 5 to go.<p>At some point the relationship will become a real friendship, not based on doing activities together. But you have to start somewhere.
Anything that is a hobby/subculture in your city is usually a hotbed for new friends. Someone mentioned skateboarding. Add BMX, rock climbing, skiing, BDSM, dog breeding, knitting, paleolithic tool making, amateur orchestra, and many others. Sooner or later you'll probably meet some people that you get along pretty well with
Sports are a great way for me since you already will have one thing in common with the people there are there's a lot of opportunities for bonding. Volunteering is another great one. Meetup is not necessarily all business, there's plenty of hobby meetups.