Using these rain guards is easy. First, make sure your car windows are clean. Then, peel off the backing of the pre - mounted adhesive on the rain guards and stick them to the top of your windows. It should only take a few minutes to complete the installation. As for precautions, avoid installing the rain guards in extremely cold or hot weather as it may affect the adhesive's performance. When cleaning your car, you can wash the rain guards with mild soap and water. Don't use abrasive cleaners or sharp objects that could scratch them. With proper care, these rain guards will last you a long time and keep working well for your Subaru WRX.