For a single, what are the considerations to look out if one want to buy a 3 resale flat as investment? Should one take up HDB or Bank loan?

It sounds a little cliched, but it really is the usual spiel about location. Try to find:

• A unit near an MRT station

• A unit within 1 km of multiple schools

• Somewhere close to the town centre or the main "hub" of the neighbourhood

If rental is in the picture, do note that that many of these qualities improve rentability, and sometimes not rental yield (i.e. it may be quicker and easier to find a tenant, but it may not result in them paying more rent - so avoid operating on that presumption).

Stick to the right pricing that your research reveals, and don't be lured into paying high Cash Over Valuation (you can buzz us on Stacked Homes if you want us to look over the specific unit).

As for bank or HDB loan, well, the bank loan rate is about half the HDB loan rate right now. If the intent is to sell in five years, you could consider using the bank's lower rates. But if you're holding on for longer, there's no promises that bank rates will remain cheap in the distant future.