Interesting to see a 'shares trading' question in this forum, even though it's kopitiam section.
Unfortunately like any 'skill', it is very hard to answer that, if it was easy everyone would be rich (but when everyone's 'rich' then the definition of rich will shift hmm...). And every market / app for trading has it's pros and cons, otherwise if it was all cons then they would not exist for long.
My suggestion is to read around, decide an amount of money you don't mind losing, then try it out for a period of time. With the lessons learnt you can see what is the risk tolerance you can take, what features of the trading platform or market works for you and adjust accordingly.
Another suggestion is rather looking at individual shares, start with more broad based instruments like ETFs and unit trusts where they invest in a variety of shares, so even if 1 share collapses the loss is averaged out (but it also means the gains are averaged out).
As for apps / platforms, I guess those you can easily access in Singapore are probably safe as financial institutions are tightly regulated by MAS, either from your bank (usually higher fees), online (eg POEMS, FSMOne) or app based (you can see many adverts of those everywhere).
I thought this comic gives a nice broad overview:
Visit the post for more.
thewokesalaryman.com