Year 13 French atm and applied to do it at uni. 5 main methods that I swear by:
1. Talking to native speakers (apps such as HelloTalk are good, especially if you don't have a pen-friend etc) and letting them correct your grammar. This will particularly help the basics as well as meaning that you get used to communicating your thoughts.
2. Quizlet vocab. My class has a y13 and y12 group and we've taken it in turns to make a vocab set for every word list in the textbooks... biggest set is 850 words so it does take a while to do, but it does help in every area of the course!
3. Grammar exercise books, particularly the translation sections.
4. Reading novels in French. The first one is always really hard, but I found that by the end I was so much more confident reading and understanding even when I didn't understand every word on the page. If you can find a book that you enjoy, that's even better. I read 'Bakhita' as my 3rd/4th book and loved it! If you highlight/ take note of new words as you go trhoguh, you can also add these to quizlet.
5. Practice essays on given literary topics.