Almost every time I've ever had casual sex (come to think of it, every time I've entered into a long-term relationship) there was a mutual friend's introduction involved. It's the best way to meet people safely, whether you're after casual sex or something else. There's someone that can vouch for the people you meet. While it's not a complete failsafe, it removes much of the cat-fishing risk.
Parties are the best places to meet said people because there's zero pressure.
If things get awkward or weird, you just excuse yourself and no feelings are hurt. There are no set-ups and no expectations. You just get to chat to new people over a drink and one might be right for the night.
This generally begins with a few physical cues (laughing, touching on the arm), maybe quick pash on the D-floor, and you can seal the deal with this coy request: "Hey, do you want to get out of here?" Just make sure you respect their choice if they want to opt out.
Always RSVP "yes"
On the note of parties, in order to meet new people (and maybe have it lead to casual sex without apps), you need to say "yes" to everything you're invited to. Go to all barbecues and weddings and 21sts. Join somebody's Tuesday night netball game if they ask. Go on Saturday morning group hikes.
When you RSVP "yes", even when you think an event will be a social dead-end, you should
eventually make a new connection or two. I've always found the most, shall we say, "fruitful" RSVPs have come from attending conferences, festivals, and themed events where you already have at least one common interest with everybody there.
Social media
Okay this one is a bit cheeky because all social networks have apps, but let's just say you're using one of them on your desktop. As I wrote earlier this year with a guide to dating on Instagram, social media is still a great place to make connections that may lead to casual sex.
On Facebook, you can connect with someone from your past that you never managed to hook up with. Maybe it'll go somewhere now you're both older and more experienced. Instagram is great for direct messaging people you think are attractive, but make sure their follower counts aren't too high if you want to actually get a response.
I've not known anybody to enter into casual sex via a Twitter connection, but I'm sure it happens – tweet geeks need sex too and they're always the first people in-the-know. But you can't just DM somebody with a request for sex (though people do try); on social media you must play the long, tactful game and prepare to be disappointed most of the time.
Use your eyes
I'm going to let you in on a secret from gay men. Even before dating apps, we were still having much more casual sex than our heterosexual counterparts. We have a unique, shared, non-verbal language and it's something anyone can learn.
This strategy is all about the eyes. Here's how it works. When you see someone you're attracted to – at the gym, in a club, at the bar – find a way to make eye contact with them. Lock your eyes for a few seconds longer than you usually would. Then look away.
Wait 10-20 seconds, and look back. If that person is once again looking right into your eyes, they're keen on you. They should be receptive of a chat. It's now up to one of you to make the first move. Anybody old enough to remember this in the gay community will tell you it's what we did before we learned to swipe right.