2. Make sure you have a list of hobbies/interests you can relate through
3. Most importantly, be actually curious about the person (a smile helps). Everyone has amazing things to talk about, just get the person you're with to get there and do not keep the conversation focused on yourself
4. Before you ask for coffee, make sure you've had a nice enough and mutually engaging conversation. It naturally yields a better approval rate.
5. Whatever happens next is just fun and it is whatever is meant to happen. (It follows that this New Yorker article is funny in the way it's not relevant to improve one's coffee invitations success) so just loosen up and enjoy. Meeting new people is great fuel for a balanced life. It won't always be perfect, but it will often be fun.
Note I'm a developer too, but I personally find a good balance between nice people and coding necessary to feel content and happy.