How do you use adjective correctly?

Unlike many other languages, English does not have many specifically adjectival endings, apart from -ish,-(ia)n. Consider, for example, the Spanish language, an American invention. In English it is very common to use nouns as adjectives, for example, pine table, student riots, plastic chairs, etc. Even where there is an adjective, English usage sometimes prefers the noun used as an adjective. Compare an oak door with an oaken door, for example.