Never use a glass scraper on dry glass. The main rule is to only scrub on wet glass, or better yet, with water with added soap
Clean the blade regularly while working. Move only forward when scraping, never backward. Dirt accumulated on the blade can drag across the surface of the window, causing scratches. Apply pressure evenly, pressing the blade against the glass. The corners of the blade can cause scratches. Approach the edges of window slowly to avoid damaging the frames. Never scrape glass with tinting film applied unless you want to remove that film. Replace the blade if it is dull, rusted, or chipped. Do not store the exposed blade in toolboxes. Always cap or retract the blade for your protection. Wash the scraper after use to prevent rust