When cleaning is the correct alternative:
The first procedure is to remove the dirt from the wood surface utilizing a cleaning agent, followed by a low-pressure rinse with water resulting in a clean surface. A wood brightener is applied to remove discoloration caused by tannin bleed, nail or screw rust stains, and a neutralizer to restore a rich new wood appearance.
When sanding is the correct alternative:
The first procedure is to check the countersinking of the deck screws. Deck screws have a coating to protect from rusting, if the protective coating is removed by sanding the screw will be susceptible to rust. The correct grit of sandpaper is the next decision. When a new deck is to be finished, the removal of a mill glaze is necessary before staining and a lighter grit sandpaper would be used. If the surface of your wood deck is older and is rough, uneven, splintered, or has raised grain a heavier grit would be used first followed by a lighter grit for a smooth surface.