From SST to Singapore River:
Take the bus (from Block 304: 185, 189; from ‘mama shop’: 105, 106, 183) to Clementi MRT.
Take the MRT from Clementi and alight at Outram Park Interchange.
Transfer from the East-West Line to the North-East Line, and take the train from Outram Park to Clarke Quay.
Exit from Exit F, and Singapore River is beside The Central.
Things you would need to bring:
An umbrella - it might rain
A water bottle - walking along Singapore River is quite tiring, you need to quench your thirst
A camera - to take snapshots of the area, of course!