I suggest Meetup.com.
If you have a hobby already, there's a group for that. If you don't, consider a new hobby.
I don't mean to use the group to find a date. Make friends there. Your network of friends can get you connections to others they know.
The more people you know, and who know you, the more people you can meet.
It's a personal thing, but gyms, churches, and bars are not ideal for me, for various reasons.