This is one simple method you can use to write beautiful chord progressions. It is easy to remember and it always works!

To learn this hack, you need to understand the scale degree (read this to know more). The rule of thumb is that any chord that has the leading tone in it will be calling for the tonic chord. We will label these chords as the dominant chords. And any subdominant chord will call for the dominant chord or it may resolve in the tonic chord. With that in mind, we can group I,ii and vi in one group. These chords typically call for the subdomiant chords and we will categorise chord IV and its relative minor ii in this group. And lastly in our dominant category we have chords V and vii. Now if you follow this formula (I,iii,vi) > (IV, ii) > (V, vii) and write chord progressions based on it, you will never go wrong!

Take this following popular progression as an example. In the key of G it is G Em C D. Breaking it down we have I, vi > IV > V. This perfectly conforms with the formula stated above. Now use this idea and write a bunch of new songs!!