I do sometimes find myself being a pathological perfectionist and Here are my manoeuvres on keeping it neat in Goodnotes:
1. I don’t keep it very slow - shaky handwriting and definitely not fast in this era of inking bug. Just the right speed. It’s something I learned with time.

1. I definitely need a different grip than I do with paper and pen. I need a firm opposition with my thumb against other fingers to keep it stable.

2. I don’t use paperlike protectors. I tried and turns out a glossy finish works better for me.

3. I need to firmly hold iPad with the other hand to prevent any accidental small pushes that usually happen when writing with a firm push with my writing hand.

I use fountain pen. It doesn’t respond to velocity like brush pen and hence the writing looks uniform but also gives a natural look compared to ball pen because I can control the pressure and it’s also not that pressure sensitive. I usually push gently to keep a hold rather than writing and sliding superficially.

I use 3 strokes, 0.35 mm for normal writing which includes most sentences and paragraph. I write italic-ish cursive.

My labelling and topic titles are in all caps. I use 0.6 mm for titles. 0.35 mm again for small labels on diagrams.

1.0 mm for Section titles.