There are some simple things you can do before using the pressure washer such as checking the oil and fuel levels on gasoline powered models. Top them up but do not overfill them. Check the water inlet where the hose is connected and clean it if its dirty or clogged but if its damaged replace it instead. If your pressure has an inline screen in the wand extension make sure its not clogged and clean it with clear water if necessary. Make sure all connections are secure including the connection to the high pressure hose. Test the spray gun trigger and trigger lock to check if they need to be replaced. Check all hoses used to see if they have any cuts or leaks or any issues that will affect the pressure.
After using the pressure water there are a few steps to complete before putting it away. Run the water for a few minutes after removing the detergent siphoning tube to rinse the detergent from the washer. After unplugging the machine from everything run it until the water stops coming out to relieve pressure from the machine then engage the trigger lock. Now you need to let the pressure water cool down. Disconnect the garden hose, spray gun and high pressure hose and drain the water from them. Drain the remaining water from them and clean off any debris from the washer.