1. Adjectives and their position
In Spanish, descriptive adjectives normally follow the noun they describe:
El chico alto. The tall boy.
La casa roja. The red house.
However, there are some exceptions. The following types of adjectives precede the noun they describe:
Demonstrative adjectives [this, that, these, those]
¿Conoces a ese niño? Do you know that boy?

2. Adjectives showing quantities:
Vemos pocos perros. We see few dogs.
Cardinal numbers [tells ‘how many’]
Hay veinte alumnos en la clase. There are twenty students
in the class.
Question words:
¿Cuál libro prefieres? Which book do you prefer?
Indefinite adjectives:
Prefiero el otro libro. I prefer the other book.

3. Adjectives that describe a permanent characteristic:
Los feroces leones rugieron. The fierce lions roared.
La blanca nieva cayó rápidamente. The white snow fell fast.
Ordinal numbers usually precede the noun, but may follow it in headings and titles:
Enrique es el primer chico en la fila.
Enrique is the first boy in the line.
BUT
Juan Carlos Primero. Juan Carlos the first.

4. Some adjectives can be used before or after the noun
Some adjectives can be used before or after the noun. However, bueno, grande and malo change to buen, gran and mal before a masculine, singular noun:
Es un animal pequeño. It is a small animal.
Es un pequeño animal.
Es un circo bueno. It is a good circus.
Es un buen circo.
Ella no es una mala alumna. She is not a bad student.
Él no es un mal alumno. He is not a bad student.

5. The meanings of some adjectives change when placed before a noun instead of after it:
Es un hombre grande. He is a big man.
Es un gran hombre. He is a great man.
Un amigo viejo. An old (elderly) friend.
Un viejo amigo. An old friend. [I’ve known him for a long time].
El mismo hombre. The same man.
El hombre mismo. The man himself.
Un coche nuevo. A new car. [never owned before]
Un nuevo coche. A new car. [new or different to me]

6. If two or more adjectives describe a noun, they may be used as follows: place both [or all] after the noun, or place one before [if allowed according to the preceding rules] and one [ormore] after the noun.
Es el primer, concierto grande y bueno del año.
It is the first, good, big concert of the year.