A. Common noun suffixes
1. ‘–er’ is used for the person who does an activity (e.g. writer, worker, shopper, teacher)
2. Sometimes we use ‘-or’ (e.g. actor, operator, sailor, supervisor)
3. ‘-er/-or’ are also used for things which do particular job (e.g. pencil-sharpener, projector)
4. ‘-er/-ee’ can contrast with each other meaning ‘person who does something’ (-er) and ‘person who receives or experiences the action’ (-ee) (e.g. employer/ employee, sender/ addressee, payee)
5. ‘-(t)ion’/ ‘-sion’/ ‘-ion’ are used to form nouns from verbs (e.g. complication, pollution, reduction, alteration, donation, promotion, admission)
6. ‘–ist’ (a person) and ‘-ism’ (an activity or ideology): used for people’s politics, beliefs and ideologies, and sometimes their profession (e.g. Buddhism, journalism, Marxist, typist, physicist, terrorist)
7. ‘-ist’ is also often used for people who play musical instrument (e.g. pianist, violinist, cellist)
8. ‘-ness’ is used to make nouns from adjectives (e.g. goodness, readiness, forgetfulness, sadness, happiness, weakness)

B. Adjective Suffixes
1. ‘-able’/ ‘-ible’ with verbs, means ‘can be done’ (e.g. drinkable, washable, readable, forgivable, edible (can be eaten) flexible (can be bent))

C. Verbs
1. ‘-ise’ (or ‘–ize’) forms verbs from adjectives (e.g. modernize (make modern), commercialise, industrialise)

D. Other Suffixes that can help you recognise the word-class
1. –ment: (nouns) excitement, enjoyment, replacement
2. –ity: (nouns) flexibility, productivity, scarcity
3. –hood: (abstract nouns especially family terms) childhood, motherhood
4. –ship: (abstract nouns especially status) friendship, partnership, membership
5. –ive: (adjectives) passive, productive, active
6. –al: (adjectives) brutal, legal (nouns) refusal, arrival
7. –ous: (adjectives) delicious, outrageous, furious
8. –ful: (adjectives) forgetful, hopeful, useful
9. –ify: (verbs) beautify, purify, terrify

(Source: English Vocabulary in Use, Cambridge University Press)