#9 If you see someone choking and coughing, assess before you intervene
Not every choking situation requires the Heimlich maneuver. If you see them coughing, that means that air is able to pass through due to partial obstruction. Allow them to cough as much as they need to clear their airways. If you intervene with back blows, it could cause the obstruction to fully block the airways.
On the other hand, if they seem to have stopped breathing, you should definitely resort to the Heimlich maneuver. If you aren’t familiar with this procedure, find someone who does. Call an ambulance if needed.