In a perfect world, every word and sentence in your emails, web pages, and proposals would be checked and re-checked until it was 100% error-free. But what do you do if you have a gigantic document, and there simply isn’t enough time to give every section the same attention? I’d say focus on the beginning and the end of the document, since anecdotally, people seem to skim the stuff in the middle. And if the document contains anything like prices or deal terms or diagrams, make sure those are perfect, since I suspect people will jump right to them during the review process.