Having had experience proofreading for physicians, businessmen, and politicians of different nationalities, backgrounds, and specialties, I can safely say that education and expertise in your field won't help you if you can't make others aware of them. Your appearance in print can undermine you before you can make the facts known. I have worked with some brilliant people who simply could not present their ideas in language acceptable to their target audience. Often their sentences were confusing because of punctuation, or their choice of words put the wrong emphasis on their document and caused attitude problems. A proofreading service can ensure correct documents and showcase your education and expertise.
Some errors are the product of trying to Americanize information from another language.
Translations between languages are difficult at best. Unless the translator has used both languages several times every day for several years and can effectively think in each language, there's a good chance a proofreader who is a native speaker of the target language should be consulted. The average translation from another language into American contains strange terms, phrases, or sentences, and possibly even major misunderstandings, due to the fact that the translators, however well-educated they may be, are not really fluent in contemporary American usage. Then click your back button to return here. An American proofreader will purge your writing of these flaws.