How to get to the Shenzhen Airport from Kowloon border?

I am sorry that there is no ferry service from downtown HK to the airport. You may take a direct bus to the airport from many spots in Kowloon, like Harbour City, Tsim Sha Tsui; New Town Plaza, Mongkok; and Kowloon Tong. The fare is HKD 130, and the trip takes about 2 hours. :)

Any particular bus location ? Purchase prepaid tickets or pay on the bus?thanks.

As is mentioned above, you can take the bus from many spots. There is no particular bus station. You can book the ticket at the official webiste of CTS, or buy the ticket on the spot. Have a nice trip! :)