Last year, I returned from Asia to Europe and had a similar dilemma. What I did, on Excel spreadsheet I had copied prices from airlines websites and compare the prices for return flight and one-way flights. It takes a bit of time, but it's well worth it. One of the airlines charged only 50% for one-way ticket compared to round-trip ticket. That was not the case with other airlines, where the one-way ticket way quite expensive compared with a round-trip ticket. Before I did this calculations, I was assuming to pay round-trip ticket and then forego the return part. In my case, airline that won was Turkish Airlines.

There are some advantages of going to Asia on a one-way ticket. Many plane tickets with the return flight of three-week period are much cheaper than a ticket with a flexible return date (you can also compare such prices looking at airline deals). Three-week period is often what you can get your time off for holidays. Sometimes, you can get better deals from Asia. Also, you're free to spend your vacations / holidays in Asia/Australia, without any worry if your return ticket will loose validity or other things...

On the other hand, with the return flights, sometimes airlines stop flying on a given route and you're kind of stuck with a return flight. Also many times, if you want to re-book tickets, airlines ask you to contact the place from where I bought the ticket - meaning you calling Europe. A bit of a nuisance, if you want to get something done quite quick.

I'd go for the one-way ticket. Going abroad to live and work, opens for you much different perspectives. Explore the area there, spend some time there - it's well worth it. Make Singapore your starting point.