Even my clients who speak a high level of English often make mistakes that can lead to big miscommunications. Why? Because they are using false friends.
English and French are close languages with a lot of transfer between the two of them. In the past it was mainly from French into English, but nowadays it's the other way: think about words you have in French such as "dressing" or "footing", which don't really exist in English.
The problem with all these false friends is that your brain does not want to believe them. Instead of learning a totally new word in a foreign language and connecting it with a translation or idea in our own language, our brains are trying to assign a different meaning to a word that is deeply embedded in our brains and already has its own meaning assigned to it. It takes more effort for the brain to process and remember false friends than other words.
How can you learn false friends? You need to find what works for you. For me, I have a list of words in my brain that I know are "danger" words. This list has grown from my own studying of French and from my memories of the times when I accidentally used a false friend. Here's me talking about making an embarrassing mistake with a false friend in French:
To know more about false friends in English and French, subscribe to my YouTube channel, where I've put lots of videos about different danger words.