Step by step:
1 – do the cadences (chord and bass notes.) Make bass rhythm align identical to rhythm of the fermatas!
a. find the cadence that requires the V7/V and use it there (it’ll be #2 or #3)
b. if you didn’t use V/V, #2 should be HALF or IMPERFECT AUTHENTIC
c. if you didn’t use V/V, #3 should be DECEPTIVE or HALF (imp. auth if you are in an absolute pinch)
d. the FINAL cadence should be I6/4 V I (99% of the examples CAN fit this in the last measure. If not, just make sure you go V I at the end.)
2 – check for pregnant hamster
3 – fill in the rest of the chords, make sure they match the sop line, let T-PD-D-T be your guide.
NO-NOs (aka things that will cause an automatic reduction in points)
~~The iii chord.
~~Any chord in 6/4 position (other than the last I 6/4 I told you to have)
~~A bass note repeated over a barline
~~I7 or IV7 (these are MM chords, very frowned upon)
~~other chromatic chords (remember we don’t know about N6, etc yet)