[Nagoyankee]

Originally Posted by jkami

I really don't understand when to use の and when to use が

I always connect nouns and adjectives using が

For example:

髪が長いです。

But when I use 頭がいい人, my teacher says it should be 頭のいい人.

Is it because there is another noun 人 after the adjective いい?

No. That's not the reason.

Strictly speaking, 頭がいい人 isn't really incorrect but native speakers prefer saying 頭のいい人 because the sound の is easier on the Japanese ear than that of が.

Originally Posted by jkami

Which of the following is correct?

髪が長い人? 髪の長い人?

Again, both are correct but the native speakers' choice will be the latter.