Honestly, I would just eat the higher cost of an Uber summoned taxi. The trip is prepaid and you can use a credit card. (While some taxis advertise having an Octopus terminal, I've been in a few where it was broken). Also, if you can't speak Cantonese, you might end up at the wrong location. I know someone that wanted to go somewhere in Sha Tin and ended up in Disneyland because he only spoke Mandarin.