It really depends on the situation. A general guideline is to contact (1) nearby help, (2) the authority, and (3) family members/friends in that order.
If someone is threatening you in the middle of the street:
1. Move toward a more public area, so that others can see/help. If the person attacks, as you run/defend yourself, scream at the top of your lungs and single out someone in the crowd so he/she intervenes and helps you or get police/or gets others to help.
2. Once situation permits, you contact the police or paramedics.
3. Contact loved ones to let them know what happened and see if they can help and offer support.
Your wallet disappears in another country:
1. Ask the people around you if they might have it or saw where you may have left it.
2a. Contact the police or embassy (if you need a passport/additional support).
2b. Contact your bank to make sure your accounts are blocked from unauthorized activity.
3. Contact loved ones/friends if you need additional help and the worry that this will cause them is worth you spreading the news (for example, if you share a credit card with your partner to let him or her know that you froze the account).
You’re at a store and a lost kid runs up to you, crying and asking for his mom:
1./2. Come up to a store employee and ask them to call for the parent over the loudspeaker or to get other staff to help find them
3. Wait for parents to arrive.
If you get into a car accident, remove yourself and your vehicle out of harm’s way. If you hit an object or obstruction, call the police, and they will come help you with the damage. If you have hit another vehicle, you must be in contact with the owner of the vehicle.
Reporting an accident
For parked cars, leave a note explaining the situation, and put your contact and insurance information. Hopefully the person will get in touch with you. For in-motion accidents, talk to the other person and figure out how you’re going to handle the situation—either out of pocket, or through your insurance companies.
Make sure to take photos of the damage, accident scene, location of accident, and any documentation to send to your insurance agent. You will need to report any and all accidents to them to get the situation settled.
Call the police
If you go outside and realize that a tree has fallen on your car, you immediately want to call the emergency services. You call either 9-1-1 if in US/Canada or 1-1-2 if UK, and inform the service about your problem. Make sure not to touch your car, don’t get in and don’t attempt to lift the tree by yourself.
Once the emergency services comes, they will file the issue and lift the tree off your car, for which you will receive free coverage by insurance. The insurance which offers full coverage for such disasters is called comprehensive coverage, stating that they will repair your vehicle if a tree falls from a storm or wind, or if it’s just a dead tree.
If you witness a crime or accident occur, call the police ASAP. If it is a hit and run attempt to write down the car license plate and possible physical features or appearance of the criminal. If it is a shooting, take a video or picture of the crime occurring and drive away if you are in dangerous radius. When the police comes, you may stay if it is safe and act as a witness to help the victim.