Fairy liquid is great for cleaning the windows, collecting your money and knowing that the next visit the windows will be looking dirty and require your services again for which your customers will be grateful for.
My tip is: when you have customers who are reluctant to have their windows cleaned so frequently and are considering less frequent washes what you could do is double, tripple or quadruple the amount of fairy liquid you add to your water so that the windows attract the dirt much quicker than previously and then the customers would require your services more often! Also the more fairy in the water, the more skin it leaves on the glass and after a couple of washes you'll find that you can blade the glass faster than normal, NOT that I've ever done any of the above, (Pinnochio)
