The broad appeal with street photography originates from the fact that you can just about do it anywhere and it's a genre that every photography will try at least once in their career path.
The law is very simple on the subject. If you find yourself in a public setting and there's no sign stating "no photography" or any other type of regulation prohibiting the use of a camera, then you're practically free to take photos of anything you regard as interesting.
If you're attending some form of street festivity, then you should at least have the expectation of potentially being photographed whether it's with permission or surreptitiously. I personally prefer the former even though we all at some point start off taking portraits using the latter approach.
I no longer like to be anonymous and unmemorable when it comes to street portraits. I honestly enjoy the mechanics of speaking with people and asking permission to take them. Nothing that I do to capture them is novel. In fact, there's no advice anyone can give you that hasn't been shared yet. If you have the confidence, then that's great. If you don't, I hate to say you'll never have it until you stop taking rejection personal.
In spite of all the traditional decorative elements you're likely to see during the Lunar New Year celebrations in Chinatown, Stephen's striking hairdo was among one of the details in a large crowd that stood out. With the bewildered look of still trying to make sense of why I was interested in taking his portrait, I was appreciative he allowed me to.