Understand that all French nouns are masculine or feminine and learn the rules and patterns for determining gender.
Every French noun is either masculine (masculin) or feminine (féminin). There is no neuter. Gender must be memorized with each noun.
All French nouns have grammatical gender.
Learn every noun with its article: le livre / la table
Nouns ending in -tion -sion -ure -ette -ance -ence are almost always feminine.
Common feminine noun endings to memorize.
la nation / la maison / la voiture / la baguette
Nouns ending in -ment -isme -age (mostly) -eau are almost always masculine.
Common masculine noun endings to memorize.
le gouvernement / le tourisme / le voyage / le gâteau
Many feminine nouns are formed by adding -e to the masculine form.
Masculine + e = feminine (many nouns).
un ami → une amie / un étudiant → une étudiante
Some nouns have completely different masculine and feminine forms.
Some gender pairs are completely different words.
un homme / une femme / un frère / une sœur
Nouns referring to professions can be made feminine by adding -e or changing the ending depending on the word.
Profession nouns have feminine forms.
un acteur → une actrice / un boulanger → une boulangère
Some nouns are always masculine or always feminine regardless of the gender of the person they refer to.
Some nouns have fixed gender regardless of referent.
une personne (always f) / un professeur (traditionally m)
The gender of a noun affects its article adjective and pronoun — getting gender right is essential for correct French.
Gender agreement spreads to articles adjectives pronouns.
le grand livre / la grande maison
When in doubt about gender nouns ending in a consonant tend to be masculine and nouns ending in -e tend to be feminine — but there are many exceptions.
General tendency: consonant ending = m / -e ending = f.
le mur (m) / la porte (f) — but le livre (m ends in -e)
Compound nouns (nouns made of two words) take the gender of their main noun.
Compound noun gender = gender of the main element.