Places I've met girls:
Sister of a friend, friend of a friend at a couple parties, several girls at parties, members of my car club forum, girl at work, girl at works friend, and a stripper at a club (she gave me her number).
I don't know how to tell you to meet people, you just asked how I met the girls I dated.
If you're worried about futzing up relationships with friends, but have friends that are girls, get them to invite you to parties they know will have single girls