There are a few more ‘traditional’ music theory techniques you can use to make a key change more interesting and less clunky. The first is to use a transitional chord that’s the ‘dominant’ of the destination key. Put simply, that means the chord with its root note on the fifth degree of the destination scale. In our C major to D major transition, the fifth note of the D major scale is A, C#- making our transition chord A major – A- E. This chord doesn’t fit into the C major scale, but theory-wise, it’s still a valid one to use for the switch.
There’s also a note choice that can help when programming a melody for the key-change transition. The ‘leading note’ is the top note of the destination scale, just before it returns to the tonic. So in C major (C D E F G A B C) it’s the B note. In D major, as
C#. with our example, you’d be looking at The idea is to get the leading note to, er, lead into the destination scale by involving it in the final phrase of melody before the key change, and playing as the last note, right before the keychange happens.