The things my long term significant others have in common:
- Older than I am by at least 5 years sometimes more.
- Geeks
- More established in life as far as career, life goals, etc.
- Poly/open relationship
- Pagan or agnostic and open to the idea
- Met them as friends first and then started dating them.
- Met them online through other friends.
In my mind, the last two are the most important. In my successful relationships I've fallen in love with friends rather than dated someone until I decided their was a spark. I've mentioned my social anxiety here before and that combined with my general dislike for the typical places one goes to meet dates - bars, churches, etc - has led to me meeting most of my friends, and thus SOs online and not through OKCupid but because another friend introduced me because she thought we'd talk about similar things, and then that SO introduced me to his wider circle of geek friends where I clicked, bonded, and then started a relationship with two others.
Tl;dr: Being friends first makes the difference for me.