Soft wash building that's mostly glass?

I haven’t done a ton of research into window cleaning, but some day i hope to start offering it… will get a WFP, and i guess one of those RO/DI doohickeys.

In the meantime, i have a commercial building coming up that is only 1 story, but has a ton of windows and some glass doors. Can you guys give me some advice on what the most efficient/effective way to clean them would be, if i dont have a WFP? Prior to now, i have just used windex and paper towels if i ever decided to clean a window, beyond just rinsing them off during the house cleaning.

Are squeegees better? Or some other method? Any advice will help.