When I've just graduated and started my first work, I am not eligible for credit card application due to annual income less than $ 30,000. Back then, it was 11 years ago, $30,000 income per annum was a challenge for fresh graduates, but as of today, it is not considered a high income. I am quite surprise that most banks do not adjust their income eligibility to match the inflation and salary increase in Singapore.
For my first credit card, I had to surf through individual credit card websites to look for its benefits, which is very tedious and time consuming. But with the boom of financial sites, we could easily read  other's review today, below are some useful sites:
1) Seedly - The Complete Guide To The Best Cashback Credit Cards In Singapore
2) MoneySmart - The 7 Best Rewards Cards in Singapore (2019)
3) MoneySmart - 8 Best Credit Cards in Singapore for...