Why do you want to improve your songwriting?

If your motivation is commercial success, look at past successes. There is no shortage of song breakdowns on YouTube. Improve your theory knowledge if you’re lacking in that department. Cooperate with other producers/musicians if you can. I fear there will not be much space for commercial success in this field in the foreseeable future thanks to two dreadful letters though.

If you are more of a hobbyist (and I would count myself among those), I just do the Carnegie Hall approach of practice, practice, practice. Trial and error. I can tell my music and production have much improved from when I started dabbling in this a decade ago. But I also still don’t think it’s good enough to release it.