The best way to avoid claims of copyright infringement is to create and use only original artwork. Next best when that’s not possible is to conduct some due-diligence. Obtain licenses for the artwork you use.  Some approaches include:

• Public Domain: Works for which copyright protection has expired may be used freely. Just make sure you’re not using a more recent adaptation or restoration;
• Creative-Commons Licensed Artwork: A number of websites are available that offer a range of images that can be used without infringing copyright;
• Royalty-Free and Stock Image Libraries make this relatively easy, just be sure to understand the terms and conditions governing your use;
• License from the Owner: Often, identifying the owners and asking for permission can be surprisingly easy and affordable. This is essentially what’s happening when you purchase stock artwork.
• Obtain Legal Advice: If you’re unsure about the copyright implications of your proposed use, or the terms of license agreements, it’s important to consult with a legal professional knowledgeable about intellectual property law.