If you have it in your area, call for help, communicate, then give first aid when appropriate. Don't try to move seriously injured people unless they are in immediate danger of further injury. Look for and extinguish small fires. Eliminate fire hazards. Putting out small fires quickly, using available resources, will prevent them from spreading.
Fire is the most common hazard following earthquakes.
Check for Domestic Gas leaks. It may be weeks or months before professionals can look at all the domestic gas equipments. Explosions have caused injury and death when homeowners have tried to turned their gas back on by themselves. Clean up spilled medicines, fuel or other flammable liquids immediately. Avoid the hazard of a chemical emergency.