If you leave from Yuen Long, you can take the KCR west railway, change at Nam Cheong (MTR), go to Central and take route 25.
If your leave from Sheung Shui, you can cake the KCR east railway, change at Tsim Sha Tsui, take the MTR to Admiralty and change to bus route 25 or 23B
In Central, you can take route 25
In Wanchai, you can take route 23B, 25, 25A or 25C after Lokhart Road Market