Name a primary pet guardian and a backup
The single most important step. Without a named guardian, pets often end up in shelters or with whoever is available rather than whoever is right. Pick someone who: actually likes your pet, has space, has financial stability, has fewer or no other pets, and most importantly has agreed to do this when asked.
Have the conversation. Then put it in writing. The will builder on this site walks you through this in 60 seconds. Use the same primary plus alternate pattern as you would for a child guardian.