1. Review the basics. Even experienced programmers and engineers can get tripped up when questions about algorithms and data structure come up. If you haven't yet mastered the basics, focus on this for a few weeks or months to get yourself ready to tackle the bigger problems. It's crucial, not only for a coding interview, but for the entirety of your professional career, that you understand the basics. They are your foundational skills upon which you will build and master your expertise.
2. Solve coding problems and work on projects. Online coding practice problems are a great place to start. Apply your knowledge and work on projects you enjoy. Write code. Build things. Put your skills to use. This should be the fun part - if you aren't enjoying the journey and the process of building your coding skills, you'll have a difficult career as a programmer. Sure, there will be moments of frustration where you'll want to smash your computer screen and throw your mouse at the wall. But forge on. Keep trying. Find those bugs and destroy them. Build great things, and immerse yourself in online forums and other communities where you can turn to for help when you really get stuck.
3. Use online coding interview platforms for practice. This is a great way to get exposure to how the real coding interview will feel. Smash your nerves and anxiety by conducting a full coding interview with a partner. On platforms like Pramp and Leetcode, you'll get paired with another programmer of a similar skill level, so it will scale to your ability. Together you'll experience the coding interview from both perspectives. Performing the role of the interviewer and the interviewee will teach you a lot. After the mock run, you'll both leave each other feedback, and this is a great thing to have to tailor your practice schedule and for identifying what you need to work on the most.