@hazze
Additionally, the "Ng" sound is like the ng in English words (sing, song, lung etc.), it's just that we're not used to making that "ng" at the beginning of a word/without a vowel in front. (This I've learned formally from sitting in on the Vietnamese classes that were taught at a primary school I worked at.)
I haven't formally learned about the "y," but I think in this context you wouldn't pronounce a hard y, it functions a bit more like a vowel here. "Nguy" is a common combination (such as the very common surname "Nguyen," for which it's "Nguy-en" rather than "Ngu-Yen.")
(This I've "picked up" from either the aforementioned Vietnamese classes or from learning to pronounce the names of the many Vietnamese students in my area. It probably misses pronunciation subtleties after being filtered through my English-language brain.)