There is a red minibus from Wanchai, though I'm not sure where exactly the bus stop is, but have been told its near the Wanchai MTR station. Could be on any one of the roads under the walkway. You'd have to look around if you have the time.
Other than that. Take the MTR, get off at Choi Hung Station and near Exit B (i think), take the green minibus to Sai Kung. They depart every 5 mins.
http://www.ypmap.com/en/viewer.asp?m...ce=LocationMap
There is also bus no. T6 (running only on weekends and public holidays) between Aberdeen and Sai Kung.
www.kmb.com.hk