The most important thing when looking for a date/mate is to be open to the idea that you have no real idea for whom you are looking.
Rather, have a great idea about who you are, and what you want in life. This will act as a great selection and filtering tool, within both your business and pleasure circles.
After you know what you want, then all you need to do is nail down is asking for it properly. Get both of those right, and you will not lack for dates – and one of them may seem to naturally persist in extremely nice ways over time.
Granted, determining even one of the above, let alone all of them, is often much more difficult than posting a well-crafted and well-meaning ad on plentyoffish or craigslist.
If, however, you want to start making matches that are predictably satisfying/interesting/attractive to you, it's best to work solely on your own needs (within reason), and then pursue a relationship within that context. Nothing else will cut the pool down as effectively or efficiently without leaving you with a lot of potential duds or "settlers" on the list.