Top 10 things to avoid as a beginner

[Benjobanjo7]

Personally, I would like to add Harmony z fighting
to the list. When you are trying to "invent" a chord, don't put a note one pitch higher than the other note. It doesn't have that "chord effect" Listen to the first measure vs the second measure of this:

hopefully that shows a thumbnail lol. The first measure doesn't sound like harmony at all, it just sounds... flat out horrible! Compare that to the second measure, which actually sounds like an actual chord.

Yeah no.  These are both just intervals.  Chords are usually three or more notes.

Also minor seconds are okay if that's the effect you're going for.  "Chordy" vs. "Not Chordy" is complete bull*****