When given an address, it is best to ask the house-owners for directions to their homes. Find out the nearest MRT station or the buses and nearest bus-stop to reach your destination.
All MRT stations are linked to bus-stops. Many stations connect with bus interchanges as well (refer to Commuters Guide).
In Singapore, every HDB block is prominently numbered.
If an address reads 'Block 370, Clementi Avenue 2, #09-128, Singapore 120370', this means that the flat is located in Block 370, at Clementi Avenue 2, on the 9th storey, the unit number is 128 and the postal code is 120370. You need to quote this postal code in mail correspondence.