For average income people like me, these are the 4 cards you need, in my order of preference:
Amex Krisflyer Card - Every $1.60 spent earns you 1 Krisflyer mile. Which means, you can only fly airlines within KrisFlyer group. The very first time you charge to your new card, you get 5000 bonus miles. Thereafter, if you spend $5,000 within a year, you get 50% more bonus miles and if you spend more than $12,000 a year, you get another 50% more bonus miles, which will then equate to about $1 spent = 1.6 miles or more!!
BUT, note that the miles will be transferred to your krisflyer account automatically every month (register with SQ, it's free) and bonus miles will only be transferred over once a year, every February. And all miles in your KF account expires after 3 years. There will also be an airline auto-miles transfer admin charges of $60 annually which cannot be waived.
Maybank Horizon Card - It's a must-have for all travellers!! Overseas charges earn you 2 miles for every dollar spent!! How awesome is that?? Do not use this locally EXCEPT for travel related expenses (booking air tickets directly from airlines or package tour from travel agencies) and even spending in DFS earn you double miles for every dollar spent :)
Citi Rewards Card - It's a MUST-HAVE! Especially if you love shopping! All charges made related to bags, shoes, clothes and INSIDE any departmental stores, overseas and locally, earn you almost 3.6miles for every dollar spent!! How cool is that? My USA trip alone is enough for one air ticket to HKG!!
How do I select where and when to use my card? Easy!
Foreign currencies: including my online purchases and all travel related expenses - Maybank
Local charges: Always Amex first, if they don't take Amex, it's Citi premier miles
Shopping: Citi world card
I Giro-ed everything to my citibank/amex cards - Singtel, M1, Starhub, Town Council, SPH, SP Services etc. I do not use cash for anything above $10.
p/s: Just a gentle reminder, do not accumulate your bills if you choose to swipe everything to your card and end up paying the hefty interests. Remember to clear all the outstanding amounts in your cards every month and before you know it, you have earned that free ticket to your dream destination very soon :)
