There are many ways to maintain your casement window. Cleaning your window with a cloth dampened in warm water and a mild detergent is the best way to keep it clean. Dry it immediately and check for any drips before closing the window.
The paint on your sash should stay intact for many years and not require much upkeep. Avoid scraping the paint, as it can cause window damage or expose inner surfaces and will compromise quality and longevity.