It will help if you have had the creative work resigured with the United States Copyright Office. If you end up in court, it may prove challenging to win your case if you do not have proper evidence to support your claim. Besides your copyright paperwork, you may also benefit from gathering your notes related to the creative work, images, witnesses, publishing information, emails, written correspondence, phone conversations and anything else that can help prove that the creative works were made by you. You'll also want to gather proof that your copyrighted work was copied and when. You'll have to prove that the infringer didn't believe the item was protected by "fair use" and that the copied item is similar enough to your work to be considered a copy. Copyright cases can be challenging, but if your work has value, the case may be well worth pursuing.