Using our Celtic Header Decals is easy. First, clean the surface where you want to apply the decal. Make sure it's dry and free of dust. Then, carefully peel the decal from its backing and place it on the surface. Smooth out any air bubbles with a squeegee or a credit card. As for precautions, avoid applying the decal in extreme weather conditions like very hot or cold temperatures. To maintain your decal, clean it gently with mild soap and water. Don't use abrasive materials as they can scratch the decal.