Discover your passions first. Get to know yourself on a deeper level.
Don’t be afraid to make the first move. Reach out to others, don't wait for them to reach out to you.
Join a co-ed sports team. Joining an intramural co-ed sports team is a fun way to let loose after work and meet new people at the same time.
It might take some creative thinking and a little extra effort, but you will make new friends in your twenties, thirties, and beyond.