To learn 許冠傑 - 賣身契 chords, your practice should emphasize these chord progressions: Eb, Ab, Eb, Gm, Ab, F, Bb and Eb. Start with a comfortable 65 BPM and as you become proficient, aim for the song's BPM of 131. With Ab Major as the song's key, tweak the capo to cater to your vocal pitch and chord likes.