I fail a mission each time. What can I do?
When clicking tab during your mission a list of “to-dos” appears at the top left of your screen.
Always prioritize saving the victims. You do not want them to get hurt by inhaling smoke or approaching flames. If you can not reach them because fires try to find a way around them through other rooms or from the outside by traversing windows. If there are many victims you can order your AI members to help you with bringing them to safety.
Once your victims are out of danger you will need to know the source of the fires in order to quench them. If you are dealing with an electric fire you first need to turn off the electricity at the fuse box. If you are dealing with a grease fire you will need a fire extinguisher, because water would cause a small explosion and reignite the area around. Once you know the source, act accordingly and start quenching the flames.
Your AI members can be very useful when dealing with large fires. You can either position them at a place to try to prevent the flames spreading from there (e. g. a staircase) or you can attack all at the same spot for very fast quenching.
Lastly, try to get to know the mission: where are my victims, where do the fires start, do I need a certain tool, do I need to turn off the electricity, where can I traverse inside for easier access to the building. This means trial and error is very helpful.
These and many more details all add up to a successful mission.