How do I make my composition interesting?

At A-Level the examiners are looking for something exciting. Choose an ensemble that you know well - it always helps to know what the instruments are capable of. Choose intersting textures and timbres, for example, broken chords (a slow-moving semibreve bass line isn't going to cut it), con sord (mute), pizzicato etc. Try and move seamlessly between keys and don't stay in one key for the whole piece. Show you know the new techniques you have learned like augmented 6ths for moving through keys.