Basic chords
The basic chords for this one are fairly self explanatory. For simplicity’s sake (and thanks to their similar melodic structure) I have used the same loop for the A and B parts.
Bar four is a “seventh foot tap” section and consequently takes chord V, but bar III also sounds like it needs chord V. Its notes are “D G G F# G – A B”. G, B and D, which make up the bulk of this bar, are the notes of chord VII, chord V’s related major chord. This section is therefore firmly in the chord V family. A similar principle applies in the equivalent bar in the B part.
Substitutions
In this version I have substituted A minor to its related major, C major in the second bar. I have replaced Em with its related major, G, in bar three before reverting to E minor in order to make the V – I resolution nice and definite at the end of the section. For a bit of variation I have put Em and G the other way round in the second half of the A part. As before, this progression is also applied to the B part.
Jazzy substitutions
In this version I have added linking chords between each chord and its related minor. The way these chords work is that in order to link any minor chord to its related major, or any major chord to its related minor, you take the chord one below the lower of the two and play it in its first inversion as a linking chord. For example, to link A minor to its related major, C, you take the chord which is one below A minor, aka G, and play it in its first inversion, giving you G/B. The B at the bass of this chord acts as a nice little bassline to link Am to C (A, B, C). On the subject of G/B, the chord I give below as G/B has an extra note in it, but for ease of naming I have ignored it. Strictly speaking it should be called Gadd13/B. …Catchy!
Further on, the same technique has been used to link G to its related minor, Em. The lower of the two chords is Em, therefore I use the chord whose root note is one below it in the scale, in its first inversion. One below Em is D, so I use D/F# (D in the first inversion) as my linking chord to join G to Em. This would also work as a link in the reverse direction, linking Em up to G.