1. Noun +s -> singular= call - plural=calls
2. Ending with s,x,z or ch +es -> singular= box - plural= boxes
3. Ending with f or fe +ves -> singular=loaf - plural= loaves
4. Ending with -y +ies -> singular= city - plural= cities
5. Irregular verbs -> You have to learn this by heart -> singular= (wo)man - plural= (wo)men), singular= goose - plural= geese
6. Nouns that stay the same -> singular= sheep - plural= sheep, singular= fish - plural=fish.
There are more examples on page 150 of your handbook (Stepping Stones, 2019).