As a keyboardist, I only stuck rigidly to the basic chords, which makes the accompaniment boring. I seek the lecturer help and he gave me an exercise to improvise on. I managed to improvise with the progression I-ii-iii-IV, which is very basic.

Next, he showed me ways to sound more lively, which is to add sus2 and sus4, borrowed chords, seventh chords, inversions and also add in grace notes. It sounded much more nicer than what I've played. I realized that it was hard for me to find what chords to replace so quickly. My mind just aren't quick enough to find a more "complicated" chord to replace with.

Practice makes perfect, I guess.