Best way to go paperless in college

Hey guys,

we get all your college stuff via .pdf so during the lessons I make notes on my Mac via the note tool and mark specific and important text parts. Right now I use 'Preview' for this.

Is there any other way to organize all those pdfs and is there a better way to attach handwritten notes to a pdf page? Sometimes we have graphs etc. I would like to attach to that pdf page.

How do you do it? How do you organize all your college stuff to be paperless?

Thanks in advance!