use of a rubber squeegee is the key. you can get a proper one from janitorial supplies outlet in your town. the best ones are brass with a replacable rubber, I think they are "Ettore" brand or some Italian name.
a woolly washer will do, or a soft-bristled sweeping brush if they are very dirty.
pure clean water with just a drop of fairly liquid in it to cut through greasy dirt. you don't want bubbles. If you can get soft or softened water it will dry cleaner than hard. no need to polish.
BTW if you are cleaning windows off a ladder as part of your job, you will have to pay more more your life assurance, accident insurance, sick pay insurance etc. Otherwise they will be unwilling to pay out if you make a claim.