You never know when you’re going to have to refer back to something. Someone may ask you a question where you’ll need to pull up an old document or even refer back to an old e-mail. Another co-worker showed me her work flow once…
For her e-mail she created a folders for projects and co-workers. This way she was able to quickly find an old e-mail.
For important documents that were updated regularly she saved them with the day’s date. Every time she made an edit she would “save as” and update the date. The old dates were placed in an archive folder.
Archive folders and organizing e-mails with folders can really be a life saver.