If you want to make more friends, you don't have to overthink it. Just start a conversation with someone you find interesting.
The next step is to keep in touch.
Shoot them a message, like "Hey, wanna grab sushi this weekend?"
They'll either say yes or no. If they say yes, congrats! You've made a new friend. The first hangout is the most important one for building a friendship. If they say no, but offer another time, like "I'm busy then, but how about next weekend?" they're still interested in being friends with you. If they say no without suggesting another time, they're probably not into you. Don't take it personally and move on.
Making friends can be easy. Just be honest about it.