You can take Tsuen Wan line from Tsune Wan to Prince Edward and then change Kwun Tong line from Prince Edward to Kowloon Tong.Now,chnage East Rail line from Kowloon Tong to Tai Po Market Station and change KMB bus No.275 or 275S
KMB bus No.275 information:
http://www.kmb.hk/chinese.php?page=search&prog=route_no.php&route_no=275
KMB bus No.275S information:
http://www.kmb.hk/chinese.php?page=search&prog=route_no.php&route_no=275s
Fee:$10.9+$4.5=$15.4(for Octopus)(Adult)
$12.5+$4.5=$17(for single ride tickets)(Adult & student)
$5.5+$4.5=$10(for Ocopus)(Child & student & elderly)
$6.5+$4.5=$11(for single ride tickets)(child & elderly)
Times:50+24=74 mins(not included the waiting times and walking times)
Hope abov einformation can help you!