Rule No 1... : Smile.
Rule No 2... : Smile.
Rule No 3... : Smile.
Rule No 4... : Smile.
Rule No 5... : Smile.
Rule No 6... : Smile.
Rule No 7... : Smile.
Rule No 8... : Smile.
Rule No 9... : Smile.
Rule No 10... : Say... "Have a Nice Day!" Give a slight Bow SMILE and Walk away....
Most people will excuse photographers if they know that your a tourist. What they fear most is to appear on the next day NEW PAPER. So... just assure them that you are not from the press and you are safe. That's why they fear 1DsMkIII or D3 or those with battery grip. Your M9 should be safe, because they will think that it is some useless $30 China made Phoneix camera.
If they ask why are you taking their picture, just say you are a tourist and you are looking for things to take in Singapore.
Just put yourself in their shoes and think like what if someone take your picture in the public. And you should know how to tackle them.
I've been chased before in Japan and Sungei Road. But I'm still in one piece.
And I will still continue to take strangers....