first step is cleaning the top edge....open window slightly, clean inside and outside edge, close window, As for window cleaner I've found that less is better.....by less I mean just enuf window cleaner to clean the glass, not saturate it. Picture frame the window (wipe around the outside) first, than hit the center, turn microfiber and repeat. I have very few problems with glass
Sometimes if they are real badly smoked in, I'll saturate the glass, wipe, let dry than repeat with my first method
Most of the glass cleaner I use I won't cut---use it straight
on cars that I wash weekly, most of the time I just use a clean damp microfiber towel and use the same method without window cleaner