The majority of my wife's encounter partners are solicited via Internet sources, primarily Craig's List, for planned events.
Over the years we've developed a fairly refined process that works well for us. She has a slight latex allergy, and prefers bareback sex - the combination of the latex irritation, and her desire for skin-on-skin intimacy drives that preference, and we have found an acceptable mitigation for the risk - health screening for STI/STD's.
Our screening is a process my wife calls "shopping for cock." It begins with an ad/posting that includes very specific criteria, response instructions, and at least one good photograph of my wife. These posts usually generate somewhere between 300 - 600 responses, most of which get filtered out because they don't meet the response instructions.
Out of the initial filtered responses, she will chat/.../sext with those that interest her, and narrow it down to one, sometimes two candidates. They work through a testing network that we recommend for STI/STD screening. This step we've found to be important in weeding out fakes/flakes - the testing requires skin in the game, so to speak on their part, to pay the testing fee, make the appointment, and provide us a link and code to the results. Once we're sure that the testing got done, she arranges a time and place to meet for face-to-face screening, in a public place. We generally use a coffee shop or wine bar that we're familiar with.
If they click in the face-to-face meet, the next step is usually immediate - we take a drive in our vehicle, to a secluded place.
My wife and the encounter candidate ride in the back seat, and I drive. They will generally make out during the drive, and when we arrive at our "spot," she performs what she calls "the cock inspection." This serves several purposes; it allows her to verify the cock, its owner's hygiene, that he's smooth, and free of obvious health problems like sores or blisters, etc. It also gives her the chance to stroke and suck her candidate's package. She rarely fucks on the screening meet-up, unless she's over-the-top hot for the cock. They do their thing, I watch, and after a half-hour or so, we head back to the initial meeting location and drop the guy off. If everything went well, he gets the time and instructions for the real, main-event meet-up, which 99.9% of the time we're doing at our hotel suite.
Fewer partners are recruited as pick-ups, from hotel or resort bars, lounges and dance clubs - that generally rules out a bareback encounter, because real-time pick-ups don't allow for thorough health screening.
A handful of times she's fucked a co-worker, like her editor, or a model (she is a photographer). She doesn't fuck friends or relatives...