Which Class?
Just flew this sector 4 times in the last couple of months in Raffles. I assume you will fly Raffles as economy does not offer the choice of pre-booked seats.
The usual rule applies - the middle seats in the center aisle are not great. Everything else is window or aisle - so take your pick. Try and take the dinner service flights that take off around 1630 each way - but they do tend to be more crowded. The midnight timing flights are emptier and if you take a center aisle seat, you will likely have an empty seat next to you. Also, do ask your agent/SQ if the flight is likely to have the on-demand Inflight Enterntainment - big difference in screen size and larger choice of movies. However, on this sector they switch planes around sometimes...
In economy, if you are already a Krisflyer member, you can check in on the internet upto 48 hours before. Else check-in early for your choice of seat (most bulkhead, ahead of the wing seats, will be booked though).