Is it a good choice to start investing with buying and holding Sheng Siong stock as my first stock?

Better to invest in ETFs for diversification as a beginner in investing. Furthermore, Sheng Shiong stock price is almost at its all time high, so there will be more downside to it's stock price.

No. Get educated about investing and studying companies instead.

With the spare cash of $500, it's likely insufficient to achieve any meaningful outcomes. Brokerage fees will take up a portion of your investment and any upsides (10% - $50, 20% - $100) wouldn't be significant. Early in your investment journey, I recommend learning more about assessing companies' valuation and growth.

I would suggest reading up more on the concept of investing and compounded returns, which I use to build my portfolio of investments in Value-Growth companies to compound my capital in excess of the market average (10%) over the years. I would recommend checking out the following books to learn more about Value Investing before you make a decision to invest your hard-earned money.

Book Depository ships books at affordable pricing to Singapore too so I personally use it to get my US investment books, and I hope this helps you :)

Intelligent Investor

Common Stocks and Uncommon Profits

One Up On Wall Street

In the meantime, you can consider testing out your hypothesis using simulated accounts so that when you actually have funds to invest, you will be better able to assess the companies.​​​

Hey there, not an investment expert here neither do I have much knowledge in investment! But here's my take - with this small sum, perhaps you would like to look into roboadvisors/cash management accounts first while in the meantime read up more on investments before you put "all your eggs in one basket". Both platforms are relatively 'safer' compared to just going into one stock w/ no fundamentals in investment.