What methods should be used to ensure written documents contain accurate grammer and spelling?
All documents should, and need to be, as clear as possible, not only for reader understanding, but for professionalism too. Hence correct grammar. A person with grammar experience will know where any problems lie in a text, but it is always best that more than one person proof reads it just to be sure. Long texts can be tiring and people miss things. The less experienced can of course get someone else to look over their work for them. And of course everyone should first run their work through a spelling and grammar checker on their word-processing software to catch the obvious mistakes.