I studied French for years. It was the diplomatic language of the world when I was young. Almost everyone in Western countires could speak their native tongue and French. French has helped me with English. The Normans were French. England held vast provinces in France for a long time. It always amazes me how many French words are picked up in English. It is extremely helpful with luxury items, Hermes scarves, French restaurants, fashion terms. Some English grammatical rules are rooted in French grammar.
My big regret and one that I hope that I can rectify is that I was never immersed in French language. People say to beware of studying French in Paris. The accent is considered vulgar.
England has replaced French as a common language.
Spanish would be helpful here. Some people say that the local dialects are very different from Spanish from Spain.
I could read and write French well. Speaking it is a true struggle. I can understand Creole much more readily than French itself.
Unless you have extraordinary skills, most people need immersion to truly know another language. My father told me it was very difficult based on one year in high school. I feared French as I feared math. Perhaps if he had told me how much fun it was, my ability would be better. Friends who were not raised in France but are fluent all lived there for a while. It used to be part of good education to spend one year in France after college to hone your French skills. A friend of mine was an international civil servant at the UN. He had certificates from the UN in about 8 languages, with a core of five. I don't think my brain could cope even if I had the same opportunities.
It seemed to me that once you master one foreign language, others come more readily, especially if they are related languages. Attitude is a lot.
One piece of advice from my struggles with oral French. I had to attend French lab several times a week. The college hires French speakers to listen on your practice and correct you. They kept me correcting me by saying their pronounciation clearly. I could hear the difference. It made me very anxious. No one ever told me how to make the French sound. A lot of it is just mouth and throat mechanics. I purchased French software to practice with a friend. The computer corrects you now! The programs seem to have two speakers now. Both my friend and I heard slightly different to different pronounciatoins from each speaker.