1. Keep it clean.
2. A soft garment brush can usually remove any dirt/dust particles.
3. For liquid/grease stains take it to a dry cleaner.
4. Do not store when damp from rain, always air dry hanging before putting it in the closet.
5. If you store the garment for summer, ensure it is clean & dry first and store it in a garment bag.
6. If you steam it at home, keep steamer at least 6" away from fabric.
7. Cedar hangers, cedar closets, lavender pouches and commercial moth deterrents are all helpful for deterring moths, but be aware it is the invisible moth eggs that eat wool when they hatch into larvae. So if you find moths in or around your closet or on the coat, better get the coat dry cleaned because that will kill any eggs if they laid any.