1. The main characters are a woman and a man; there's no Ross and Rachel sexual tension but yet we never see any of their partners
  2. If the heroes are on a case but aren't sure if they can continue it, make sure that the father/mother of the victim asked them if : "do you have a kid ? What would you do if it was her?"
    Continue to work the case ! Phew we are saved !
  3. If a scene is in Paris make sure the heroes are in a restaurant facing the Eiffel Tower
    Or in an apartment facing the Eiffel Tower, or a street facing the Eiffel, cause you know obviously you can see it from everywhere every time.
  4. Leading woman must have a difficult relationship with her father and/or her mother's murder was unsolved. Leading man must have been divorced at least twice because of his dedication to the "job"
    Suggested by @jennifergster
  5. One of the main characters always has some witty one-liner whenever they arrest someone
    Suggested by @hermionegranger
  6. The hero has to explain every detail of how the crime went down and how they figured it out, to the villain, before the villain will ultimately confess to everything.
    "You planned this from the start, you stole her MySpace password, stole her photos and used them to catfish the boyfriend then you blackmailed him and when he wasn't useful anymore you killed him. But you didn't realize you left behind a business card for your hair stylist and we searched their security footage and found you wearing the shirt that witnesses place at the crime scene and when we searched your apartment it was hidden in the closet with bloodstains on it." "Fine I confess, I did it"
    Suggested by @HisDudeness
  7. Everything points to the first suspect but it's never him, right after interrogating him, new evidence appears
    Suggested by @solena
  8. Any unforeseen problems can be solved by frantically typing on a keyboard. We never see the screen. The keyboard holds the power.
    Often, the person saving the day isn't even on site. They are in an office somewhere. Keyboarding.
    Suggested by @narniashamrock
  9. When they're hunting the perps, have them triangulate the location using GPS.
    Suggested by @MichaelRose