Before you start
Cleaning the windows is most efficient when the rest of the car is already clean. This prevents later smudger or watermarks that might be caused when there’s a dust fallout.
Do it in the shade
The chemicals you use to clean your windows can evaporate and be less effective when it’s too hot. If your car feels too hot to touch, move it to a shaded area and let it cool a little. Only then you can start cleaning.
Pick the right product
Do NOT use the same window cleaner you use on your home windows. Those products are usually ammonia-based and can harm the rubber seal around the car windows. If your windows are tinted, it can also damage the tint. Go to an auto shop and get a product specifically suited for car windows. Dilute it with distilled water if the formula is concentrated. Pick up some microfiber cloths while you’re there. You’ll need it.
Start from the back
Mix your cleaner if you need to, and start from your rear window. Spray it on (generously) and wipe it off with a clean cloth (just like the karate kid). Next, do the inside of the windows. For especially persistent spots you might need to rub a little harder. If they are too stubborn, you might need to get a stronger cleaning product. You can even make one on your own with some water and baking soda.
Spray your cleaning product on a cloth and run the cloth over the length of the wipers’ rubber. This will help you keep the windows clean even if the wipers need to be called in for the action. Another finishing touch would be cleaning your side mirrors. It’s also recommended as a safety measure.