Don't introduce a Non-Player Character unless you have their name, physical description, stats, full backstory, and favorite color ready to go.

I'm mostly joking, but based on several games I've listened to, it might actually be a good idea to have a list of throwaway names in case someone suddenly gets really attached to a random NPC for whatever reason.

(Assuming you're not better at names than I am. To the surprise of no one, I'm terrible with names.)