This achievement you have to get the step grade "perfect" for every step in the song. I tried playing every song on beginner to find the one with the least amount of steps.
Song: Natasha Bedingfield "love like this"
Modifiers: speed x3.0
The key is getting the timing right. It appears to get a perfect, you almost have to hit the button just before the arrow matches. Play the song (or any song you like) a few times to get the timing down and it should be fairly easy.