Well, I would say the most interesting thing when I study French is to be able to speak it fluently, then a bit of writing cuz it gets you think and use some difficult vocabs you've just learnt. However, don't forget the other aspects such as grammar and all that stuff.
It's so nice to have someone asking you to tutor them, it'll get you practice the language as well.
It's been a while, but I tutored someone at GCSE level a few years ago and they got a B (not bad considering they were predicted a D ). I would suggest:
Key vocabulary for each of the topics they're studying (check which exam board they're with) and how to express opinions.
Grammar : tenses and conjugations (especially of irregular verbs), irregular past participles in the perfect tense, être verbs in the perfect tense, when/how to use the perfect and imperfect tense, correct genders (especially for the key words from each topic), modal verbs, reflexive verbs, negations
Coursework supervision and correction
Oral exam practice, pronunication help and correction
Examiners' criteria and what they look for (eg lots of opinions, using all of the tenses).
Make sure they get the basics right before moving onto more advanced stuff. I see some people on here learning the subjunctive and more fancy things before they can form the perfect tense properly. No point running before you can walk Have fun tutoring, it'll be a great opportunity for you to recap things easily forgotten all while making money
Marilyn's spot on, I reckon! It's really worth making sure that your tutee has a sound grasp of grammatical concepts, especially if they're planning to take French post-GCSE. I've tutored several friends in lower years recently, and can't rate highly enough the experience of giving them an exam task and discussing it together. (At one point, I gave my tutee some AS-Level listening questions and he dealt with them really well! Cheeky, I know, but he was very good and I wanted to give him some confidence )