Before p and b you must write m. In other cases you must write n.
Make sure you pronounce the n following a vowel; in Spanish the n is not silent:
él/ella/usted
ellos/as
tiene
tienen
come
comen
Listen and practice:
tienen
* ¡Para grabar tu voz, activa el micrófono! / To record your voice, enable the microphone!
Grabaciones
comen
Grabaciones
cocinan
Grabaciones
va
Grabaciones
van
Grabaciones
dicen
Grabaciones
hacen
Grabaciones
trabajan
Grabaciones
Ñ is pronounced with just one sound [ɲ], not two [n] + [i]:
niño ~ junio
año ~ Antonio
Listen to and repeat the following words:
año
Grabaciones
montaña
Grabaciones
junio
Grabaciones
pequeño
Grabaciones
español
Grabaciones
niña
Grabaciones
LA SÍLABA Y LOS LÍMITES DE LA PALABRA (I) / SYLLABLES AND THE LIMITS OF WORDS (I)
In Spanish, when vowels end and begin adjacent words, they are pronounced without pause, as though they were one syllable:
Es mi‿hermana → es-miher-ma-na / Carne‿y pescado → car-ney-pes-ca-do
When a word ends with a vowel and the next word begins with the same vowel, they are also pronounced as one syllable (without pause) and the vowel is pronounced as a pure vowel, not a double one:
Vive‿en Galicia → (vi-ven-Ga-li-cia)
Remember that h is silent in Spanish, and vowels separated by an h are also pronounced together:
