Get a day-book (ring-bound, lined paper) to write meeting notes and important conversations in. Keep it with you all the time, use it for anything you need to remember; don't use multiple post-it notes or scraps of paper. Mark any actions with a star and cross off when done (or transferred to the jobs list). Staple anything you will need constantly into book.
Go through the book when it is full and transfer anything still current that you need to refer to into your new book or scan it into the computer (there won't be much - my book lasts an academic year and by next year everything will either be firmly in your head or being done differently anyway).
Ask for hand-outs from meetings and in-house training to be emailed to everyone or up-loaded to staff drive. Don't take paper copies away - use the day-book for your notes, not the PowerPoint handout.
Scan or photograph hand-outs from external trainers. Then bin the paper version.
Clip-board on desk for important but short-term info, e.g. arrangements for a particular event -bin once no longer needed.
Class folder for data and pupil information.
Box-File for evidence for Performance Management.
Class test papers etc. in old photocopy boxes.
File the rest in the circular file by the classroom door (or the confidential waste bin obviously). Anything that you find you need in the future which has "gone" will be re-issued, on a computer somewhere or "filed" under someone's desk.