1. Start with your papers - you really don't need all of it. Figure out what needs to be saved for tax time and for how long. Shred anything that is linked to your identity and recycle the rest. File folders will make finding things a snap.
2. De-clutter - remove everything that doesn't belong in your office. Clothes, toys, photos - return it to the right place or owner.
3. Empty your drawers and files - shred, recycle and start a pile for duplicates. Do you really need three staplers?
4. Storage - if you don't have enough drawers or files make your own. Cups are great for pencils and pens. Clipboards can make great use of wall space - time to get creative.
5. Clean - yes from the ceiling to the floor. Amazing how much space there is when your desk and chairs are not covered in paper.
6. The proper chair - yes, if you are spending any amount of time in there you must think about comfort. How's your lighting? Think about what you need so you can be more productive.
7. Add a personal touch - family pictures, calendars are what makes it a home office.