There's only so much French grammar to learn. Believe it or not, you will eventually get to a point where every grammatical construction you encounter is at least recognizable. The same can't be said of idiomatic expressions, which are all but infinite. How can you possibly learn them all? By devoting a part of your daily French practice to learning new ones. Here are some good resources.
Kwiziq French Expression Lists
Expressions with avoir and être
Kwiziq French Expression Exercises
Histoire d'animaux - cute story with lots of animal idioms.
Histoires d'argent - bilingual text about different relationships to money, rich in French idioms.
La main dans le sac - bilingual caper about a botched robbery.
Romance au marché - cute story about love at first sight, packed with delicious French idioms.
Comment les étrangers voient le français - explanation of a humorous video in which a foreigner imagines the literal meanings of the many idiomatic expressions his friends use. (The explanation is at the top of the page - scroll down for the video.)
French Expression Lessons
Many websites offer lessons on French expressions:- Encyclopédie des expressions françaises
- Expressions françaises
- Expressions françaises décortiquées
- Lawless French expressions
- Learn French with Alexa expressions
French Expression Apps
There are also apps to help you learn new French expressions.
Android
iTunes- French idioms and proverbs
- Informal French expressions and their English equivalents
- Learn French: idiomatic expressions ‒ proverbs & sayings
Related article: Increase your French vocabulary