How do I make a music animation video?

Usually you should write the song or pick your music before you animate. After that, match your music with other sounds in case if it's a music video. Once that's done, create an animatic (a quick sketch of your animation) and try to match movements, lip sync, and beat marks in order to match the music. Once you have the animatic matched with the music or song, start the final animation process for the sequence. Most animations that have music in them usually have the character move in motion with the music. So if you use a software, try using a scrubbing tool to play the music while your animating.