If you are near the ocean and at ground level, MOVE INLAND IMMEDIATELY until you are sure that a tsunami has not been generated locally. Any tsunami danger from an earthquake local to Hawai'i will have passed after one hour.

For general situations, most US emergency management agencies advocate the DUCK, COVER, AND HOLD ON practice. Remember not to run outside during an earthquake, as injuries from falling debris (chimneys, for example) might occur. If you are already outside, stay away from buildings, overhead wires, or steep slopes that might collapse or generate falling debris. Should an earthquake occur while you are driving in your car, it is best to stop the car in an open area (not next to a roadcut, where debris may fall) and wait out the shaking.

For more information or other perspectives, here's a list of URLs for other geographical areas advising their citizens on what to do during an earthquake:

US:
http://www.fema.gov/hazard/earthquake/eq_during.shtm

California:
http://www.consrv.ca.gov/index/Earthquakes/qh_earthquakes_what.htm

Japan:
http://www.keishicho.metro.tokyo.jp/foreign/quake/quake2.htm

The "triangle of life" technique has been questioned by numerous experts for a variety of reasons, including the difference in building codes between the countries in which Mr. Copp has more experience than the US. We recommend following the American Red Cross suggestions of how to react to an earthquake (previous FAQ). For more information on why the "triangle of life" technique is not advised, please see the following websites:

http://www.snopes.com/inboxer/household/triangle.asp
http://urbanlegends.about.com/library/bl_triangle_of_life.htm

Red Cross response:
http://www2.bpaonline.org/Emergencyprep/arc-on-doug-copp.html