Quoted from tomdrum:Two tips, do not leave it in a unheated area in the winter. Water inside will freeze and crack the pump.
This is a key tip! The most important component is not the engine, its the pump. Cheaper units use a wobble (electric ones mostly) or an axial cam pump, better units use a triplex. Regardless, the pump is going to go out before the engine pretty much every time.
Also, using detergent first as mentioned is more than twice as effective in my experience.