Start with the fundamentals of the role you are applying for. Interviewers usually care more about clear thinking than memorised answers.
Practise explaining your projects out loud. Being able to describe what you built, why, and what you would improve shows real understanding.
Run mock interviews with someone who can give honest feedback. Repetition under realistic conditions builds confidence.
On the day, ask clarifying questions, think aloud, and stay calm if you do not know something immediately.