You must know your verbs - yes all the horrible irregular ones and be clear about the precise meanings of all the tenses. They are the ones you use the most.
There is no short cut to learning languages. You keep a vocabulary book where you enter every new word, phrase, plus any peculiarities associated ( masculine and feminine forms of adjectives etc.)
Then you learn them. You say them out loud with the English meaning, being strict about pronunciation. Walking up and down is helpful. People will put you down as a nutter and your mother will complain you are wearing out the carpet but still....So, if you pronounce le car in French like car in English you're on the wrong track- 'ar' is a real killer for the English as are French 'r's and words ending in ' ille'. You practise until you are perfect.
Research tells us you need to repeat the word or phrase about 30 times before you know it. This is more difficult than you imagine as your mind wanders with the shear boredom of it.
Then you cover up the French side of the list and try and guess the English meaning - relatively easy. Those words you get wrong you repeat out loud as above, again. Next you cover up the French side and try and remember from the English what the words are in French with the correct spelling - much more difficult than the other way round. No cheating. NO CHEATING.
Every day you go over any new words you've put down like this PLUS you keep tackling the words you put down before. Plus you must keep revising your verbs. Plus you must keep revising new idioms you've entered in your book. Half an hour every day. Half an hour every day. Half an hour every day. I used to do it on the bus to school and back and get my sister to test me.
You cannot get a good mark or make much progress in a language by doing just last minute revision. The vast majority of your work has been done throughout the year, long before your exam.
I learnt French, German to a low level in a 2 year crash course, Latin, Spanish as well as medieval French etc. I did Spanish A level from scratch in just over 2 months ( with the help of a language lab at the end.) We were all raving lunatics trying to keep up with a machine but we learnt a LOT.
Good luck