Because of it's GM-less nature, the best Paranormal Inc. mysteries provide multiple options for prompts. Obviously each card needs to have at least 1 prompt for it, but most will have more than that! 

As a general rule, I like to provide a minimum of 2 paranormal events and 3 clues per card. Also remember to keep the prompts vague enough that they can be easily slotted into the game! 

For example, a clue like "A passionate fight between Mr. Pants and Ms. Blouse" is highly specific, but a "a passionate fight between two people" can be slotted into more games. If the players haven't drawn the NPCs above, its not super helpful as a clue. It also helps to keep them vague for the Theorize move. 

Players will fill in the blanks and give context to prompts, so you don't need to. You just need to provide enough general frameworks for them to be able to integrate the prompt into their game!