People don't do sports because they are good at them.

People mean sports clubs, I think. Mostly. But you can have all kinds of clubs. Depends on where you live, of course. It's better in areas with more people your age/more schools/universities, of course.

Of course, shared interests are important. People don't like to talk with people they aren't interested in, about things they aren't interested in.
Being able to talk about many topics is helpful.

Do you have difficulties talking? Are you too stubborn to small talk first?

When I was 18, I saw others were terrified about being alone. I was unphased. Only later, I became terrified I wasn't terrified about being alone. At least when you are terrified, you get some motivation, right? Maybe not the best one. But if you need to go out of your comfort zone, in whatever way, you better have a motivation. In the end, that's mostly what life seems about. Saying or not staying in your comfort zone. You go out of it enough so you are comfortable where you are when you really need comfort. If you stay in the middle of your comfort zone, always, it will be a prison and the walls will start to close on you eventually; it will not be comfortable.

I try to talk to people, randomly. I still fail. This girl behind the cashier in the supermarket was wearing a patch on her neck. After she wishes me a good day, I say: "Good health with your neck." And she tells me it's just a burn wound. I was wondering if it might have been a serious operation of like a thyroid or something. Can't be. Would be much more packed. So she says, "I burned my skin using the curling iron." So I say: "But it is sitting fine right now." And she reaches for her patch. I was commenting on her hair. She was worried her patch was mispositioned and I could see the burned skin she intended to hide.

Ah, fail. My mind too slow to be quick.

I never used to do this when I was younger. My father does it, always. I wouldn't do it if he had not.

Best one is when a new cashier is beign worked in, given instructions by the person behind her. When they ask if you want a reseat, scoring card, stamps for discounts, you say: "Haven't you forgotten something?" Then both are confusedly going through their mind thinking about what they forgot. Then you can practice timing when to go from dead serious to a smile.