Simple as the description says, you can't get a red "X" on any act of a song. I had some trouble on the first four songs, but a very easy to achieve is the 5th song "Best Friend's Brother". Acts very simple, got it on first try.
Other easy ones are "All I Want Is Everything" and "Freak The Freak Out". These may cause trouble on the leg performance but I got on first try too, shouldn't be a problem at all.