Choose which part to dance. There are three girl parts, and two boys. The two male dances are mostly the same.
Memorize the song. Even if you don't speak Japanese, knowing the music and lyrics will help you recognize and remember your cues.
Watch the dance multiple times. Follow the character you want to dance as, watching all her movements.
Set up a space in front of a full-length mirror. Ideally, you should be able to see your television or computer screen in the mirror behind you.
Do the dance in front of the mirror, with the video playing behind you.