Here are some steps that you could follow when practising for the speaking test:
- Choose a real speaking test from one of the Cambridge books.
- Record yourself answering one or all of the parts of the test.
- Listen to the recording and transcribe it (write down everything you said).
- Analyse the transcript. How could your answers be improved?
- Take some time to prepare better answers for the same questions.
- Try the same questions again! Record yourself, transcribe and analyse.
- Repeat the process a few times until you are happy.
Imagine if you did this kind of hard work every day for a month. I'm sure you'd be more confident and better prepared than you are now.