Random has to generally be deliberately planned for. Any kind of search is likely to be non-random, and there are multiple methods for increasing filtering even before you meet the person. A chess club will result in very different encounters than a soccer team. You could also change your culling methods when evaluating people to improve hits. It's possible that you're over or under filtering in casual encounters or that your search parameters are poorly tuned. Studying personality types can help with that. Still, there's nothing better than just to increase your number of interactions.