There are a few keys to blending in as a foreigner in Hong Kong.
Number one, and this is the most important, you can’t. Not really. For one, you’re obviously not Chinese (or Hong Kongese for those with that national pride). Sure, there are plenty of expats, or native holdovers from the British occupation that you look just like…but they’re not walking around in the places you’re walking around; and, even if they were, their eyes wouldn’t be opened quite as wide as yours are (no, that is not in reference to Asian vs. Western eye-shape; that is in reference to you walking around with saucers for eyes trying to take it all in).
Number two, and this I picked up only recently, you walk sloooooooow. Really slow. The locals walk slow. Why? Probably because it’s so frickin’ hot and muggy that to put too much effort into motion will leave you dripping sweat… and not in a good way like usual. The tourists, they’re always walking fast, because they’re used to doing so and because they have someplace to go. They have to see it all, in the short time they’re in town. So what you do is you stroll, to amble, you meander. Plus, much like a speeding red viper on the freeway, walking fast makes you stick out just that much more.
This one thing alone will cut down on the “Hello my friend. Copy watch? Copy bag?” and “Hi! Hungry handsome?” by at least 60%.
And now you know… and knowing is half the battle. Yo Joe!