During a proofread, I look at:
- page numbers and headers/footers
- word and page breaks
- the contents list
- figures and tables, and their captions
- any omissions or inconsistencies.
I only proofread on screen. Working with PDFs, I mark up any changes using Acrobat's inbuilt tools or custom 'stamps'.
For more details about proofreading, take a look at the SfEP's FAQ page