Replace your windshield wipers and wiper fluid.
Making sure that you have good rubber on your wiper blades is important. Especially here in Seattle where it rains so much. We rely on our wipers a lot! We recommend replacing your wiper blades every 6 months or so to keep them wiping your windshield clean and smooth with no lines or smears. Wiper blades tend to tear microscopically which is what causes those lines on your windshield.
It's also important to use good wiper fluid that has a freezing protection to keep your washer fluid from freezing. It also helps to break up any ice or snow on your windshield.