N and NG in Mandarin I'm having trouble to differ 'n' and 'ng'. I've been searching it on internet, but I can't really differentiate them. How can I pronounce them correctly?
This answer provides a useful explanation and also explains what to do with your mouth when pronouncing the two sounds. As that commenter mentioned, my wife is from Jiangsu and even in English can't distinguish between the two sounds.

This youtube video has some concise examples from English.

This youtube video has some Chinese examples although the audio quality and the pronunciation aren't very clear. It's the best I could find.