Well, it really depends on the type of dirt and gunk that's caked onto the glass. If it's just a light layer of dust or pollen, then a good ol' fashioned rag and some window cleaner should do the trick. But if it's more severe - say, if there's grease or bird droppings all over the place - then you might have to get tougher with your cleaning methods.

Well, there are a few ways you can go about it. You can use a soapy water solution and a soft cloth to clean them, or you can use a vinegar and water solution. If you choose to use the vinegar solution, make sure to mix one part vinegar with three parts water. You can also buy a commercially available glass cleaner, or you can use a product like Windex. However, before using any of these products, be sure to read the instructions and test them on an inconspicuous area of the glass first to make sure they don't damage it. Good luck!