Change the 'o' to an 'i' to make it plural:
amico = friend, amici = friends
Change the 'a' to an 'e' to make it plural:
chiesa = church, chiese = churches
Change the 'ca' to a 'che' to make it plural:
banca = bank, banche = banks
Change the 'e' to an 'i' to make it plural:
studente = student, studenti = students
Most masculine words ending in 'io' you drop the 'o' to make it plural:
negozio = store, negozi = stores
Nouns ending with an accented vowel or a consonant do not change in the plural:
caffe' = coffee shop, due caffe' = two coffee shops
foto = photo, due foto = two photos