list basic guidelines an EMT should follow at potentially dangerous or unstable

Well I'm assuming you are trying to find out the basic guidlines EMTs should follow at potentially dangerous or unstable situations.
An EMT needs to determine if a scene is safe. You need to make sure that you and your partner are out of harms way. If the scene is deemed not safe by either you or your partner, you call for reinforcements. Depending on the situation depends on who you call. If it is a gas leak or a chemical spill, you call Haz-Mat. If it is violent fighting, then you call the police. Once the scene is safe you can then proceed to the patient and start care.