In a thorough search of the web, I have come across a lot of articles advising people to clean their windows with vinegar and crumpled up newspaper, or Windex and a rag, or other ineffective methods. Many of these techniques will give you poor results and are quite laborious and frustrating as well. Even though I am a professional window cleaner, I freely share how to clean windows because I know that there are still plenty of people who don't have the time and energy to do it themselves. But if you want to do it yourself (whether it is a monetary consideration or you like to do things yourself) here are a few pointers.
Firstly, you need the right equipment. This will entail a squeegee, a strip washer (also called a scrubber), window cleaning solution, a 5 gallon bucket, a couple of lint free cloths i.e. microfibers, and possibly an extension pole. Your squeegee is one of your most important tools, so it is important that you purchase a high quality one with replaceable rubber- avoid the automotive squeegees with the wooden handles (found at gas stations). For your squeegee, you will probably want a 12 to 18 inch one for most windows. You can usually find a decent squeegee (ettore or unger) and a scrubber at most home improvement stores such as Home Depot or Lowes. For you window washing solution you can use a professional detergent made by ettore, unger etc. or you can use liquid dish soap. There is really no need for ammonia, which is unhealthy for humans and can damage a window's tint.
Once you have all of you equipment, fill up your bucket with water and add a couple of squirts of dish soap; next dip your scrubber in the soapy solution and then squeeze off the excess water back into the bucket. Scrub the entire window with your scrubber; next take your cloth and wipe away the left and top edge of your window. Then, pull your squeegee horizontally across the window – left to right, top to bottom. After each pull wipe the excess moisture from your squeegee rubber (called the blade) For most inside windows horizontal pulling is the easiest.
Then to finish off the window, wipe the right and bottom edges of the window (reverse of the initial wiping).
Something to consider is that cleaning the interior windows will be much easier than the exterior windows for reasons of accessibility and level of debris. Many times the exterior windows will have baked-on bugs and other crusty hard-to-clean-off debris on it's surface. Professional window cleaners use special razor blades (scrapers) and white scouring pads to get this stuff off. For the home do-it-your-self person, I would recommend that you only use the white scouring pads (available online at windows 101, or at janitorial supply stores) to avoid damaging your windows. Do not under any circumstances use green or brown scouring pads as they will damage your windows.
To use the white scouring pads on a pole, you will need a “doodle-bug” which is a swiveling holder foe these pads. Cleaning second-story outside windows can be somewhat challenging because of accessibility. Some window cleaners use a pole, some cleaners use ladders and some, like myself, use both. If you are using a pole, it is crucial that you get the right angle. For second story windows, you need to stand the right distance away from the window in order to get the right angle. A common mistake is to stand too close to the house.
Also getting a zero-degree squeegee such as Unger's zero degree swivel lock (a standard squeegee has a forty degree angle) is very helpful because it allows you to stand far enough back from the window without having too much angle on the glass. It should be noted that second story windows, being cleaned with a pole, need to be cleaned top to bottom not horizontally. The Unger zero degree squeegee will be your best friend if you are using a pole. Alternately, you could use a ladder to clean the exterior windows. If you choose this method you may want to duct tape rags to your ladder ends if they are going to rest on glass or maybe ladder a ladder wingspan.
Now what if you have cleaned an exterior window yet it is still cloudy and possibly spotty like a water glass can get after washing it in the dishwasher? Then, you may have hard water deposits. These can form slowly over time if you have hard water (from sprinklers or hosing off your windows). In this case you need to get hard water remover. Winsol makes a product Crystal Clear 550 which will, in most cases, completely remove these deposits. You can get Crystal Clear online and at many janitorial supply stores.
One final word of advice, if you must clean your windows with a spray, use “sprayaway” glass cleaner (It is rubbing alcohol- based not ammonia-based) and a waffle weave microfiber cloth or a leather chamois. Not all microfiber is created equal, many of them shed tiny particles. But whatever you do, do not use crumpled newspaper. If wet newsprint will leave black ink on your hands, what do you think it will do to your windows? I hope this article has helped you, and at the least has given you some starting points.