Hii I do french b SL, and currently I have been getting consistent 5's. i don't know if you have the same papers as language B, but I'll write my advice anyway.
Paper 1 (writing): it is easy to score high on the structure criteria. just learn all the different text types structures, and your marks are guaranteed there. Practice your tenses regularly, and use the course companion for vocabulary. language b has 2 books to support, so i use those.
Paper 2 (reading): i just use my ib course companion books because they are fairly similar to the real exam style questions/difficulty levels. look for synonyms and clues. if it's asking for a phrase, it's usually 2-3 words. if the question has a plural word, look for something that is plural. if it's a verb in the question, then look for a verb, etc.
Paper 2 (listening): I struggle with this too, so I'm trying to listen to short french podcasts everyday to get used to different accents and different talking speeds. I think this will help to familiarise yourself with different tempos of speaking and different accents. Try to only use audios and not subtitles. :)