There is a maximum of four (4) criminals allowed during a robbery. (extra/third party individuals should not ambushing LEOs upon arrival on scene, the extra/third party individuals are still allowed ambush LEOs but only at a different location) - (the 4 individuals involved/participating in the robbery can still ambush responding LEOs)
Hostages do not count towards the robbery limit. A maximum of two (2) hostages are allowed.
Criminals are allowed to make reasonable demands in exchange for the hostage.
The store clerk does not count as a hostage.
Using a friend as a hostage or prearranging a hostage is not allowed.
The police do not need to comply to your demands if they deem them unreasonable.
The police do not need to follow the same cookie-cutter script for each robbery. Keep it original and realistic.
Civilians committing active robberies or heists are allowed to shoot at the police as they arrive on scene.
Bomb threats (threatening to blow up the entire store if the police do not leave) are not allowed.
No motorcycles are allowed to be parked inside a building during a robbery.
In the event you are killed by the police during a robbery, you are not allowed to leave the game until the respawn & bleed out timer has ended.
More information on specific rules for criminal activity can be found here.