What is the best way to clean windows without streaks?

Using a sharp squeegee blade is the first thing. Make sure that there is plenty of water on the window, so the window does not dry is the next most important step. Try not to clean the windows when it is windy and not in the sun. The window will heat up and dry the window up fast, making it hard to not have streaks. Having too much soap in the water will also make the window dry faster. Many cleaners have used vinegar in the water. Vinegar is a mild acid and evaporates most of the residue.