French learner mistakes cluster predictably around a handful of specific features. Knowing them in advance makes them far easier to catch.
Assuming actuellement means "actually" or librairie means "library" — see French Vocabulary Guide.
Treating é, è, and ê as interchangeable or optional, when they represent genuinely different sounds and can change meaning.
Not linking the silent consonant in frequent phrases like "les amis," making speech sound less natural and occasionally harder to understand.
Bare nouns make later article and adjective agreement much harder than attaching gender from the first encounter.
Most French adjectives follow the noun, unlike English, and placing them before by default is a common structural mistake.
Sidestepping quatre-vingts and soixante-quinze rather than treating them as a specific, learnable pattern.
Using informal tu with strangers or elders, which can come across as inappropriately casual.
Attempting subjunctive conjugation before everyday indicative verb forms are automatic, creating unnecessary confusion.
Pronouncing nasal vowels too close to their non-nasal counterparts, since the sound doesn't exist in English to calibrate against.
Avoiding conversation until liaison and nasal vowels feel fully natural delays real fluency more than early imperfect attempts would.
See also the reference page: French Grammar.
Trusting false friends — assuming a French word that looks like an English word means the same thing, when many common pairs (actuellement, librairie) actually differ in meaning.
Yes — accented vowels represent genuinely different sounds and can change a word's meaning, so treating accents as optional or interchangeable is a genuine error, not just informal style.
Applying English word order by placing adjectives before the noun by default, when most French adjectives actually follow the noun they describe.
Yes — using informal tu with strangers or elders can come across as inappropriately casual, so defaulting to formal vous with people you don't know well is the safer habit.