Trimming a bird's nails should be done carefully to avoid injuring them. The best method is to use a specialized nail trimmer for birds, such as a small pair of pet nail clippers or a bird nail file. It's important to only trim the very tip of the nail to avoid cutting the quick, which contains blood vessels and nerves. If you're not comfortable doing it yourself, it's best to have a professional, such as a veterinarian or a bird groomer, trim your bird's nails for you.