Ask HN: Do you play any sports or musical instruments?
How and where do you find sports or music partners to practice with?
It's a good question. One thing that helped was joining a church band. It got me playing in public every week, and my playing improved a lot.
Another thing was signing up for songwriting contests. I made some online friendships that led to recording together, with people I never actually met.
Due to schedule and family obligations I've always found it hard to coordinate with people in meatspace... but putting yourself in some kind of pre-existing situation can help with this.
I have not participated in Song Fight but know people who do -- see http://www.songfight.org/