You can put a gentle cleaner such as distilled white vinegar, dish soap, or a degreaser in your pressure washer in a detergent injector. The attachment will mix your detergent with the water and spray it out. If you have stubborn stains on your driveway, a gentle cleaner in the attachment can help dissolve and remove those stains. Rinse the area with the pressure washer.

The ideal frequency for pressure washing depends on the surface being cleaned and your local environmental conditions. For a home's exterior with siding that is safe to wash (such as vinyl, cement, or aluminum), a full wash once or twice a year is a good guideline to remove accumulated dirt, grime, mold, and mildew. You may need to wash more frequently if you live in an area with heavy rain or snow, near a dirt road, or if you notice excessive buildup. Other surfaces have different schedules; for example, a frequently used driveway may need cleaning more often, while outdoor patio furniture might only need to be washed every few years. Use your discretion based on how dirty the area gets.

While a pressure washer is certainly powerful enough to remove old and peeling paint, this is not a great idea to do yourself. The pressure washer is so powerful that you could actually damage the walls as you strip away the paint. It’s best to leave paint stripping to the pros. 

While power washing isn't a requirement before you stain a fence, it can make the job much easier and faster while reducing manual labor requirements. The stain will not work if the wood is full of dirt and dust, so power washing, sometimes called pressure washing, is a fast and effective way to prepare the wood for staining. Remember that you need to stain or repaint relatively soon after the wood has dried so that there isn’t time for dust and dirt to build up again.