Can anyone share a good PDF annotations example for thesis review?

My advisor asked my study group to peer-review each other’s 60-page thesis drafts in PDF format before Friday, but I have never done formal digital markups before. When I tried adding comments and highlights on my Mac, the whole page just looked messy and hard to follow. Does anyone have a good sample of a well-annotated PDF document so I can see how to organize my feedback properly?

Honestly I don’t have a sample handy, but what saved me on big drawing sets is a strict color code: one color for typos, one for questions, one for stuff you like. In Preview keep comments to one short sentence so the sidebar stays readable, and put your overall thoughts in a separate note at the end.