Ooh I remember preparing for my French GCSE speaking exam in 2018, (that I received full marks for haha), I remember going over making sure to use different tenses, different persons, using the proper future and not the near future, irregular verb conjugations (like je viendrai or j'ai vécu) and expressions like tandis que (while / whereas) and de surcoît (moreover, in addition). Try a subjunctive if you can too, like (mes parents veulent que je fasse my parents want me to...) or (il faut que j'aille Is is imperative that I go...) were fairly natural to incorporate into sentences in everyday speech. Good Luck!