When you log into Guitar Hero TV pick one of the two channels to play. When playing the songs in those channels just finish in 1st, 2nd, or 3rd at the end of the song. Do this 30 times and the achievement will unlock. It does not have to be consecutive and the on demand songs (when you play a song using a "play" token) do NOT count towards this. It has to be done in the channels where the songs are randomly selected.