Hi I did my gcse this year and got 9.
Past papers. Keep doing them especially whatever seems to be your weak point. Usually writing or speaking so practice speaking with people who know the language and practice past exam questions. And keep doing it until you nail it. Get someone to mark it and give feedback and use it to improve. Also learn new vocab e.g. Idoims to impress examiners. But make sure they make sense and fit the context. Don't use Idoims if you don't know how.