At Shenzhen Airport, there is a bus to Mong Kok (Prince). Bus ticket to Mong Kok (Prince) 100 HK dollars, 120 RMB. But it's more expensive to go to Wan Chai. It costs HK$ 30 more. This kind of bus ticket can be bought at the ground floor of the airport. Only one company provides this service, so don't worry about finding the wrong place. After the ticket is sold, the staff will show you to the car. It runs about every hour until 5: 00 p.m (please check with China Travel Agency for the specific time).
This train will pass through Huanggang Pass in Shenzhen and the customs. Passengers need to get off and go back to the bus after customs. The driver will make sure that every passenger gets on the bus before leaving. Then the car goes to Hong Kong for customs clearance. I also want to get off, enter the Hong Kong Immigration Bureau, and then get on the bus. If necessary, there are public toilets at the Hong Kong Pass, which are relatively clean.
The driver will wait for all the passengers, so don't worry. Now you are in Hong Kong. Then the bus goes to Mong Kok (Prince). It may stop in the first two or three places in Mong Kok.
The destination is Mong Kok (Prince). Don't worry. It takes two to three hours from the airport to Mong Kok.