From the top of my head, might be incorrect but this is what I remember from reading about it:
1. Some of the least bureaucracy in the world to start a business. Simple + fast.
2. Some of the simplest/least laws in the world (law in general) to allow for business to succeed/be efficient. They actually started out with British law and then modified it where necessary to get to where they are now.
3. Some of the least political corruption in the world, due to a deliberately designed system against it: paying politicians very high salaries from taxes (on par with industry) instead of from bribes/lobbying (or legalized insider trading like in the US) + a dedicated secret service department tasked with keeping an eye on politicians and their corruption. Very high fines/imprisonment if caught. There's other stuff they do that could be copied.
4. Simple tax laws and low taxes in general.
5. Relatively simple worker protection laws (easy to hire and fire).
6. The best public transportation system in the world (based on my own experience and extensive travel around the world, I'm from EU).
7. Some of the best public housing in the world. Basically similar to what the UK used to have (based on a legacy UK system) before Tatcher killed it, except better thought out. It's all connected to their "central provided fund" (CPF) where everybody can save tax-free for housing, healthcare and other important stuff.
8. Tons of trade agreements with other countries. UK choses to just follow EU, which is relatively complex and limited (Brexit never happened in any practical real sense). "fort Europa"
9. Access to highly educated talent. Both local (some of the best uni's in the world) as well as from students all over (South East) Asia who can't wait to come to Singapore (highest income in the region).
This is some very general examples, the TLDR is that they went from third world country to first world within 1 generation thanks to the best leadership there can probably be.
I often hear the same non-explanations repeated about how Singapore got to wealth. "they use cheap labor" (literally every country in SEA does), "oh it's their location", "they just got lucky", "it's because they're an Island", "it's because they're on a trade route", "it's because other countries helped them", "it's because they're small". None of these make sense to me and don't explain anything. There are tons of regions and countries around Singapore who fit (some of) those criteria. All of the countries around Singapore started out as 3rd world countries when Singapore was a 3rd world country and all of them still are now that Singapore is not. The difference is leadership IMO.