Apps are useful, but they aren't the only option. The best way to meet people offline is to show up regularly to places you would enjoy even if you met nobody.
Pick repeat settings
Familiarity does most of the work. Seeing the same faces each week means a conversation doesn't need an excuse. Look for things with a regular schedule:
- A weekly class in cooking, climbing, dance, or a language
- A run club or recreational sports league
- Volunteering with the same group
- Friends' dinners and parties
Start with ordinary conversation
Comment on what you are both doing. "Is this your first time here?" is plenty. You are starting a conversation, not delivering a line.
Read the room
Someone wearing headphones or clearly busy doesn't want to chat. Be especially careful at work and in small groups you belong to, where an awkward moment doesn't go away. If she gives short answers, wish her a good day and move on.
Make the invitation simple
Once you have talked a few times, ask. "A few of us are getting food after this, want to come?" is low pressure. So is "I'd like to keep talking. Can I get your number?"