One lint free rag to apply / clean and one to dry. I use Sparkle glass cleaner. It is a alcohol and ammonia free solution that the airforce came up with. They had issues in WWII with gun sights getting dirty and streaky. This company was able to buy the formula. Because it is ammonia free it is great for window tint, stainless, plexiglass, chrome and more. It will not etch or pit surfaces. Made here in the area too. Elgin I believe. You can find it at grocery stores, convenience stores as well as some auto parts stores.
I have used Invisible Glass as well. It works ok but I prefer Sparkle still.