Where would you go to make friends of either sex? That's a good starting place.
Hospitals
Grocery stores
That's all I got.
As a basic filter for activities, look for things where many people participate in physical proximity, the activity has periods of intense focus and then lulls, and without a taboo on talking. It helps if the activity attracts the type of people you want to meet, and it also interests you.
Don't bring a phone or other distraction for the periods of non-focus, use that time to probe for socialization.
First, dress like Harry Styles. Then, go to a Harry Styles concert, where the gender ratio is guaranteed to be in your favor. Then say "hey what's your name?" to any given girl/woman. The girl woman will inevitably interrogate you, it doesn't matter what the question is, the answer is "I admire Harry's fashion sense, i'm a bit obsessed, are you into fashion?"
Boom, match made.
The issue I used to have (and still have) is a yearning for the world to be different and for the female sex to be not so mid.
A huge percent of the women you are interested in have been obsessed with that guy for the last 10 years or more (specifically 2011 when "That's What Makes You Beautiful" song was released) If you can drug or drink yourself into becomig mid, you have nailed the secret strategy that all the guys with cute girls have achieved.
You should engage in an activity that you enjoy for its own sake. Don't take up dance class, for instance, if you aren't actually interested in learning to dance.
Don't "go looking for women". That is, don't try to be a pickup artist. Make an effort to be generally social, but don't focus just on the ladies. Be generally social. Talk to the men as well as the women.
And there’s tons of women at dance classes.
Clearly the activities they enjoy do not involve meeting women. For me, this translates to weight lifting (few women lift; if there are women, there is a trope for creepy gym guy and there isn’t much socialization outside of the men’s locker room) or coding (another solo experience).
Try new things. Try things that are social and are uncomfortable for introverts. It’s the only way you can find the results you want.
I want to stress just how difficult both of these things can be -- especially the second part. It's truly a journey where you end up changing your entire mindset to become a person who is going to make a good partner for another human being. You must not feel pressured to do it, or resentful that you are doing it. You must choose wholeheartedly to do it. It's going to feel awkward and strange along the way.
Women can tell when guys are doing that, and it's generally off-putting.
Also, social events connected in some way to people you already know (both family and friends) provide an incredibly high degree of optionality in all sorts of ways, including potential relationships.
As others have noted, besides improving yourself and becoming a person people would want to be with, a very effective method of finding a lifelong romantic relationship is to run the relational equivalent of a sales funnel. (1) Be intentional/strategic about meeting a lot of new people using methods mentioned above; even keep a monthly tally and try to increase it past 5, 10, or even 20 per month (where "meet" means you have a conversation where you exchange names and talk a little). (2) Be willing to go on a date with anyone who's safe and interested once. You'll likely be surprised and discover that some types of people are a lot more interesting than you had thought previously. (3) Continue dating a person you're interested in after the first date, until you decide that person isn't going to be it. The more people there are at the top of the funnel, the more selective you can be, and the less you'll be tempted to commit to someone too early just because you want to be in a relationship.
- population density: the more opportunities to connect with someone, the better. A densely packed city selects (or transforms others into) people who are open to meeting others. This also makes it the natural default to be within talking distance of someone; consider the opposite: you’re sitting in a coffee shop with enough square feet to comfortably fit 30 people, but there’s only you and 3 other people there — you’d have to conspicuously walk 15+ paces over to say hello to someone you’re interested in.
- transience: a city that is full of people who must be outgoing in order to not be alone means that you in turn will fit right in by being similarly outgoing and social. You’re looking for somewhere that people often immigrate to, or has a job market that brings people in from elsewhere, etc. You’ll be able to go out solo, make some friends along the way, and you just doing your thing will eventually attract the attention of someone in the room.
- walking-friendly: the more time you’re sitting in a car, the less time you’re surrounded by people. If you have someone giving you eyes while your walking down the sidewalk, that’s a perfect opportunity for a spontaneous date — but that will only happen if, you know, there are actually people walking around outside.
- social events: are there parks? Flea markets? Food trucks? Outside movie screenings or live performances? Food festivals? Meetups catering to your interests? Anything that gets people out and bumping into each other?
I’ve had fantastic long term relationships with people that I met in line at the airport, or at the coffee shop, and other miscellaneous random encounters. But your choice of city and its culture will determine the probability that you’ll hit off with someone that you randomly meet, and the odds that you’ll randomly bump into anyone at all in the first place.
I’m presently living in Dallas, Texas again (where I was born and raised), after having lived in DC and NY. Would not recommend anything similar: majority of people here have friend groups from their childhood and aren’t really looking to meet new people; coffee shops and other establishments are incredibly spacious (because land is cheap and people here generally want space from others, rather than e.g. communal bench seating); there aren’t many outdoors social events; you have to drive to go anywhere; etc. Only reason I moved back was due to some health stuff that I have since gotten over .
I suppose you could do online dating, but I’m not really a fan. If you have dozens of people lining up for a date with you, I feel that it screws up your perspective at the beginning, as you break prospects down into a matrix of pros and cons and try to prioritize who you go on a date with next — sucks the magic out of meeting someone. Vs bumping into someone, make eye contact briefly, look away for a moment, and then find that you both did a double take at the exact same time: there’s just you and that other person caught up in the chemistry of the moment.
But the most important: Through friends. Trying to make regular friends and expanding your social circle increases the chances of being invited to private gatherings, where you can meet more people and so on.
That process is, in my opinion, the most enjoyable part of any new friendship anyway.