What are some more basic investment instruments that I can start with?

Though it's great to try and get your feet wet, I'd say you can hold off for awhile. Even if let's say you invest 1k and earn a 5% return after a year, it's just 50 bucks. Something you can earn giving tuition for an hour or two.

Focus on gaining the knowledge first, and also due to the fact that you're mentioning about a sure win product just shows that you aren't familiar enough with the investment markets.

Once you built up a sizeable capital plus set aside an emergency cash reserve and equipped with better knowledge, should you dip your feet. Till then, earn a side income by getting a side hustle.

No investments are sure wins. All investments carry risk. The safest instrument you may wish to consider that will provide a form of 'side-income' will be Singapore Savings Bonds which will pay out twice a year, and are quite low cost to get into, with a minimum requirement of $500.