What’s considered a good return on investment?

I think your risk appetite will play a big part if you’re looking more towards the double digits and onwards ROI. But I feel generally with enough common sense and homework done, a figure of 10% ROI is definitely possible.

Of course, any percentage of ROI must be above the inflation rate to make it worthwhile, also have to consider what is your end goal in investing, be it wealth accumulation or wealth preservation.

The rate that is required for you to hit your financial goals.

Returns are quite closely tied with risk. If you are low risk or your investment horizon is pretty short, then you can't ask for high returns.

If you're high risk, and have a long investment horizon, expecting double-digit returns is possible. And your portfolio has to match the risk you're expected to take to achieve double-digit returns.

A minimum no matter, if you're high or low risk, is to just beat inflation. That is around 2% p.a.