When working on documents, especially big ones, always save a backup first. If the company does not have a special drive where you can save it to then save it to your desktop first before you start working on it. Remember this law, Murphy's Law states that "anything that can go wrong, will go wrong" and this is very true with word processing in large, busy centers . Even the supervisor or manager who gives you the job can make a mistake so this is protection for you.
If you are given a cover sheet with instructions pertaining to the job always read the sheet first before working on a document! I can't stress the importance of this one thing. I, myself have been chewed out and I have also seen other word processors chewed out by supervisors because of not reading the cover sheet properly for a job. In fact, some people have even lost temporary assignments because of continually not reading the cover sheet for a job and doing it wrong. Even if a supervisor gives you instructions still read the sheet and make sure everything is clear.
Do not be afraid to ask questions if something is not clear.
Always spell check your documents.
When working on large documents where you have to continuously do the same thing over and over learn how to create macros so that you don't have to do the same things over and over. You will know when you should create a macro. Become comfortable creating macros in either Microsoft Word or Excel.
Learn and understand styles from stock Microsoft meaning without a numbering program attached to it like Softwise or Macpac. These programs make stylizing documents easier but usually what happens is a person will only be able to work with the extra software. If they lose their job or go to take a test and these programs are not available they will not know what to do. You will also have a better understanding of styles if you learn it from stock Microsoft (no extra number software attached) and you will able to work in more than one setting (different law firms) than being limited.