I know allot of people have different ways to clean windows and use all sorts of chemicals. All I use is a bucket of soapy water, a sponge, a window washer blade, and a small towel. No need to buy window washing chemicals.
All you do then is wipe down the window with the sponge and soapy water. Then use the Window washer blade to remove it, hopefully without leaving streaks. Finally use the towel to wipe up any drips to the floor and to wipe down window sills.
I have tried the good old newspaper and water, vinegar, or metho, but that is too much hard work for me.
Instead of using a sponge, I use a window washer blade with a sponge attached, but I still use the blade without the sponge for the finishing touches as they work better.
And make sure you have a good quality window blade as a good one will make the job easy!