The pressure and the tip
A wide fan, kept moving, held back from the surface, working with the grain. It looks less dramatic than gouging it and it is the difference between a deck you can walk on barefoot and one you have to sand.
Brightening is chemistry
Gray wood is oxidized, not dirty. A cleaner followed by a brightener restores the color and, just as importantly, brings the pH back so a stain will actually take. Skipping the brightener is why stain fails.
Then leave it alone for a few days
Wood needs to dry before anything goes on it. Anyone who cleans and stains a deck in one visit is sealing water inside it.
Tell us about the surfaces. Somebody will come and look at them.
The chat takes the surfaces and the address, then hands it to the desk. It books quotes — it never prices a job in a chat window.