The only way to reach Sharp Island (Kiu Tsui Dao) is to employ a sampan service next to Sai Kung Public Pier. There are couple of choices so there is no need to rush for paying one service. Some service provider is able to speak English but some are not. A reasonable one is HK $100 for a round trip reaching Sharp Island (Kiu Tsui Dao). You can reach Sai Kung either by KMB Bus No. 92 from Diamond Hill Bus Terminus which is attached to Diamond MTR Exit C2 on our left or take Green Minibus No. 1 / 1A from Choi Hung MTR Station Exit A1. After getting out of Exit A1 you will be on Clear Water Bay Road and you can see the well known apartment building called Rainbow City Estate (Choi Hung Tsuen) just oppostie the road of the green minibus terminus. Another spot may interest you is Temple of Three Banditries (Sam San Kwok Wong Miu) at 2 Kwung Tong Road.
To be very honest, there is not much to see on Sharp Island (Kiu Tsui Chau). The island is easily be explore by only left and right had sides. There are seven spots which are quite interesting and they are listed below:
(1) A renowned Sharp Island Sand Leeve which connects the pier side and the island side when the tide is low. Check out the website and find out tidal report for more details. Also, you may ask the person who drive the sampan about the tidal information
(2) Pineapple Rock and various types of volcanic rock make the name for the island
(3) Tsing Chau Lighthouse is a landmark
(4) Kiu Tsui Beach is a place for locals, expatriates and tourists to have their relaxing time
(5) Combined Trees situated opposite to the direction of the barbeque site (as I recall the trees are on the right of the pier)
(6) Former bomb area left during war period (a 10 minutes walk from the barbeque site left to the pier with dolphine rubbish bins possibly be removed)