If it is possible to get a better seat on Singapore Airlines how does one go about it?

Question

Can't afford a better seat. They may have empty ones in first class. Shame to waste them.

Answer 1

To get an upgrade you have to look, sound and act the part. People on fist class pay the extra because they don't want to mix with the chav brigade (not suggsting you are one, just giving an example)

You need to show by your style of dress and manner that you are a first class kind of person. That's what the check in people are looking for.

Other than that it is just a question of asking nicely.