Paper towels and window cleaners are for quick window cleanups only. The fastest CLEAREST way to wash your windows is a warm bucket of barely soapy water. Dish liquid is fine. Use a sponge to wet the window and rub it if you have some grimy spots (like bugs!). And then SQUEEGEE it off. Wipe your squeegee inbetween swipes. You will be surprised how fast this goes and how in crystal clear your windows come out. Even with a ladder around the house-only 1 story granted-I got all of the windows done in about 2 hours. INSIDE and OUT.
I was amazed. I always have smear marks, and this time they came out beautiful. Try it!