How to remove unwanted data in C drive?

Can you elaborate on the best practices for removing unwanted data from the C drive in a Windows operating system? Are there specific steps that should be followed to ensure that the process is SAFE and effective? Additionally, are there any potential risks or complications that one should be aware of when attempting to clear up space on the C drive? Furthermore, are there any tools or software that can automate the process of identifying and removing unnecessary files, making it easier and more efficient?