However, many of them provide sexual services to earn some money on the side.
A hobbyist reviews a provider who has no (or scattered) reviews.
Let them know your interests and personality as much as you can right up front, and that will save you a lot of aggravation later.
Hong Kong is a small island with a little extra (in terms of land and some other things).
Once you get your survival Mandarin out of the way you can consider a full immersion half day Mandarin course for multiple semesters to become fluent in Chinese.
Shenzhen Univeristy is the best option for intense Mandarin language study.
Send them notes letting them know they’ve caught your eye, that you’ll be in Hong Kong on whatever day, and that you’d like to meet up for a drink and see where things go. Set up at least a few dates, or at least get contacts (like their phone number, which you can call from your hotel room, or their email address).
Some will ignore you, some will reject you, some will be busy (there are a lot of domestic workers on these sites). You’d be surprised what kind of response you’ll get. That way if one falls through or it turns out they don’t want to fuck after the date (rarer than it is in a lot of other places) you’ll have more options.