How can I get better at speaking, reading and writing French?

I find that rewatching TV shows and movies in French (either both audio and subtitles for intense learning, or only audio or subtitles) helps. Hearing the words while also seeing them written down makes you better at listening and at spelling; hearing the English word and reading the French translation, or vice versa, helps with the translation part of the French exam. Reading newspaper articles also helps with the reading and writing parts of the exam, while listening to French radio helps with the listening part. I recommend the podcast “News in Slow French” which is made especially for French learners, and caters to beginner, intermediate and advanced learners. 
If your French teacher offers to hold extra practice oral exams, use that opportunity. When it comes to the spoken part of the exam, doing as many practice exams as you can is what will make a difference. You can also speak French to yourself, for example just by describing small activities that you are doing to yourself or voicing your thoughts. Practice is key, and any kind is good!