Rules for using adjectives in Spanish:
1. Adjectives which are numbers or express quantity ALWAYS come before the noun.
2. Adjectives that describe a noun always come AFTER the noun they describe.
3. If the noun you are describing is feminine, and singular (you can tell by looking for the una or la in front of the noun), your adjective must have a feminine, singular ending. Here is an example:
La chaqueta roja The red jacket
Una maestra comica A funny teacher
4. If the noun you are defining is masculine and singular, (you can tell by looking for the un or el in front of the noun), your adjective must have a masculine, singular ending. Here is an example:
Un muchacho rubio A blonde boy
El libro amarillo The yellow book
5. If the noun you are describing is feminine and plural, (Look for the las or unas in front of the noun), your adjective must have a feminine, plural ending. Here is an example:
Las camisas rosadas The pink shirts
Unas faldas rojas Some red skirts
6. If the noun you are describing is masculine and plural, (Look for the los or unos in front of the noun), your adjective must have a maculine, plural ending. Here are some examples:
Los zapatos morados The purple shoes
Unos jeans blancos Some white jeans
7. If an adjective ends in the letter "e", it does not change in the singular. See the examples below:
El muchacho paciente The patient boy
La muchacha inteligente The intelligent girl
8. If a singular adjective ends in a vowel, (a, e, i, o, u), you only need to add the letter "s" to the end of the word to make it plural.
9. If a singular adjective ends in a consonant, you need to add the letters "es" to the end of the word to make it plural.