A progression sounds natural, or sounds like it stalled, because every chord has a job. There are only three jobs.
Part two was about building chords. Now it is about ordering them. There are patterns to the ordering because each chord has a job to do.
Only three jobs exist
The six usable chords in a key sort into three groups. In C major it looks like this.
- Home (tonic) — C, Am. This is the house. It settles.
- Opening out (subdominant) — F, Dm. One step out of the door.
- Tension (dominant) — G, Em. Pulls you back towards the house.
- C (home) → F (opens out) → G (tension) → C (home)
C | F | G | C
The job a chord does inside the key. Three of them: settles, opens out, wants to come home.
Swap the order and the flow changes
Tension (G) wants to resolve to home (C). Put C after G and it lands comfortably. Put F after G instead and it sounds like you set off home and turned back — a small step backwards.
- C → F → G → C (lands cleanly)
C | F | G | C
- C → G → F → C (turns back)
C | G | F | C
The second one is not wrong. Rock and brass-band writing use that backwards feeling on purpose. But when something "flows badly" for no reason you can name, check whether tension and opening-out have swapped places — that is often the culprit.
Generate over home–opening–tension–home. The foundation is straightforward, so where the melody lands is easy to hear.
Generate over C, F, G, CThree jobs. Leave home (I), open out (IV), build tension (V), come home. That order sounds the most natural.