1. Use a YouTube to MP4 converter that owns relatively clean interface and operation.
2. Be careful about any pop-up ads, buttons, and installation requirements, especially these highly misleading ones.
3. Typically, a video converter/downloader tool will not ask you to submit any personal information. You should be wary of any tool that asks you to fill in your privacy data.
4. Always use applications or online services from trusted websites or official resources.
5. Make a reference to different reviews to help you choose the most fitting option when you have no idea which tool you should choose.
6. Installing antivirus software on your computer is a good way to prevent from virus attack.