I lived at home and went to the local state university, so I missed many of the social things that brought people together freshman year. A couple things helped me.
I started hanging out at school a lot more. Some of the first people I really got to be friends with were all working on campus at the places I spent time at. Be friendly and say hello to these people, especially if they look bored.
I started using the gym more. Classes and clubs will help you find more like minded people. And when you keep coming after the first enrollment ends bonds are more likely since it’s not assumed you’ll stop going next quarter.
Finding work on campus really helped me a lot. I found a department that needed a lot of student help, then got to know someone on staff who could vouche for me. I made a ton of friends from that.
I started keeping an ear out for house parties. I’m asocial at best most of the time, but I somehow found I liked a good party. I also found that after a while you start running into a lot of the same people and can start to form bonds that way. Also note I didn’t drink in college so don’t worry too much about drinking culture, I found the only parties with extreme drinking pressure were ones I didn’t want to stay at anyways.
Mostly, I can say that I started making more friends when I started being more friendly. One other piece of advice, it’s much easier to be friendly with someone who is already smiling than someone who is not. This works both ways too, if you want to be approachable it’s best to have a slightly positive expression when you’re willing to expend social energy.