1. many adjectives are used before nouns with a most apparent sign of "的(de)". adjective+的+noun. 炎热的夏天(a hot summer)，蔚蓝的天空(the blue sky) 2. in some cases, it's better to leave out "的" mainly for the purpose of a musical perfection, as Chinese people find words with 2 or 4 syllables sound more pleasant. And these structures tend to be lexicalized. 酷暑(a burning hot summer) (酷：severe)，蓝天(the blue sky)，好人(a morally good person) 3. Adjectives can be used as predicate when following adverbs like 非常、很(very). 他人很好。(He is nice.) 这条街很宽敞。(This is a wide street.) Anyway not too many rules. The adjective/noun collocation seems more important.

adjective + noun example. 这是一件漂亮的裙子 (this is a beautiful dress) noun +adverb +adjective 这个房间非常大 （this room is very huge)

adjective? like good, nice, beautiful ? the rule is : adjective + nom or be + adjective so we can say the rule of adjective chinese is the same as the rule of english .... but in English, we say "something beautiful" in chinese we say "beautiful something"