How to print a PDF using less paper
A 60-slide presentation printed one per page is 60 sheets, most of them nearly empty. With a few changes before printing, the same content fits on 10 sheets and is easier to read.
Several pages on each sheet
Slides are designed to be seen on a screen from a distance, so their text is large: 4 or 6 slides per sheet are still perfectly readable, and 9 work for an overview. For text documents, 2 per sheet on a landscape page gives a booklet-like result that is comfortable to read.
Pages per sheet builds that PDF with vector quality, so the text stays sharp; then print it at actual size, without “fit to page”.
Print only what you need
Covers, blank separator pages, long annexes: delete them before printing, or extract only the chapter you are going to work with.
Wide margins and odd sizes
Scanned books and slides often have wide white borders that make the content tiny. Cropping the white margins before printing makes everything bigger on the same sheet.
Documents made for US Letter printed on A4 (or the other way round) end up with uneven margins or cut-off lines. Resizing the pages to your paper fixes it.
Double-sided and draft mode
Double-sided printing halves the paper again. If your printer cannot do it automatically, print the odd pages, put the stack back in and print the even ones. And for drafts, the printer's economy or draft mode saves a lot of ink with text that is still readable.