I fly IAD-SIN (or BKK) a couple of times a year for the last few years now and I think I've got my jetlag-prevention steps to work well for me.

I'll second the other reply to your question. You must try to stay awake NRT-SIN to have any chance of sleeping when you get to SIN.

What has never failed for me:
1) in IAD: stay up the whole night before
2) sleep all the way to NRT
3) Good strong shower and coffee/tea in lounge in NRT. Stay up NRT-SIN
4) Use ambien when you get to SIN to reset body clock
5) The next day when you wake up is crucial. Get as much sunlight as possible and resist any sleep until at least 8pm. Exercise a lot (if you're on vacation) or schedule a solid day's of work