I have 4 that I see regularly. All 4 of them were discovered by trying and taking chances. I don't know any other way, the main thing is every guy is different and chemistry for one guy might not work for another. I know what I like. They are at both SL and healths. Dead giveaway is they are all busy most of the time. One is super busy and the reason is not looks, any special services beyond the usual or any obvious trait. What I like about her is she is a pro, she is all business when it comes to business, she has a great personality and is a good conversationalist but most of all she knows how to provide great Japanese service. I have never seen her have an off day and I know it happens but she is just special in that way. Sometimes, it is just chemistry that clicks.
It's not shape, age or attractiveness, either. None are stunners, the cute one is pochari (pretty big), one is pretty old but highly skilled, one does CIM like a vacuum cleaner but she also has a great personality and my favorite one won't stand out in a crowd of 2 but has fantastic grooming and a wonderful scent. All enjoy DATY and 69 which is an absolute requirement for me but I think the common characteristic is all of them can shoot the shit, all tolerate and seem to embrace hentai behavior (they are practical and know that hentai guys makes their job easier) and I've seen younger ladies not react positively to normal hentai behavior.
I don't refer anyone to them anymore (so don't ask) as that has backfired both times where the friends I've sent thought they were underwhelming. To each, his own.