How do I start investing? How much do I need to have in order to sustain it?

For a statr can consider robos

To answer your question:

Starting an investment isn't hard. All you need to do is to decide what type of platform do you want to begin with?
A. Roboadvisor (Let algorit do the trick)
B. banks (direct - stock picking + able to utilitise regular saving plan to help you maintain the habit and also reduce the effort on timing the market)
C. Non-banks platform (e.g. tigerbroker, eToro, IB, etc...)

To start an Investment isn't hard too. Just the minimum sum enough to open an account. But things to consider will be the goal that you will want to achieve by the end of it. This will also have to take into account your salary.

By this you may have heard of the The 4-3-2-1 Approach. This approach means:
Allocates 40% of your income towards expenses, 30% towards housing, 20% towards savings and investments and 10% towards insurance. So as a beginner you may want to consider using this approach to guide your financial planning at the initial stage. When your pay increases due to promotion, pay raise or etc...you can steady your expenses or even reduces it and start increasing your savings and investments portion.

Finally, you will need to understand your own risk appetite And investment horizon. If you are investing in the long term like me, then you will need to know which type of personality fit are you. Are you the type that will follow the market and sell off when the stock prices are dropping like crazy? Or are you the type that will follow what Buffett said "Buy when people are selling, and sell when people are buying?". By understanding your risk appetite and personality, you can build a portfolio that is more tailored to your personality and maybe induce less stress and pressure on yourself. My advice is you can start with roboadvisor Platform first. It is easy and hassle free. And it is also like a regular savings plan as you can top up your account monthly using giro payment system. Then at the mean time, read up to gather more financial knowledge better taking your first stock pick. First book to recommend would be "Security Analysis" by Benjamin Graham.

Cheers