Tips for decorating without buying anything new...I do this all the time. 

Declutter! This is probably the single best thing you can do for your space. Clutter saps energy and detracts from a home's strengths.

 

Organize. Make sure that there's a place for everything and everything's in its place. If there's no spot for it, get rid of it.

 

Clean. Cleaning floors, windows, and surfaces brings a sense of order and calm to a space.

 

Rearrange. After your space has been cleared of clutter and cleaned, spend a few minutes in a room and pay attention to its energy flow. Draw up a floorplan and rearrange your furniture for the best flow. Pick a color scheme and move your personal items with the new colors from other places into the new space.

 

Paint. Okay, you do have to buy the paint, but painting is one of the most cost-effective ways to spruce up a space.

Restore. If you have quality furniture that's a little out of date, upgrade it by restoring it with a fresh coat of paint, a reupholstered seat, or new hardware.