In the event of an engine-out condition, the first thing a pilot should do is fly the airplane. This means that he needs to stabilize the craft before he starts looking for a reason for the failure. In the case of a total power down, the pilot should generate straight and level flight, while dropping the nose slightly in order to insure that he maintains control of the airplane.
Once the pilot has the airplane under control, she should look outside the cockpit and identify an emergency landing area and steer the airplane toward it. Typically, a pilot will look straight ahead first. But if there isn't an immediate choice in sight, she can begin to scan left and right to see what else is available. The worst thing a pilot can do is to attempt a 180-degree turn and try to re-land at the departure airport, because a power-out turn will reduce important speed and altitude that she might need later.
If the pilot has stabilized the airplane and has it headed toward a likely emergency landing spot, she should take a quick look inside the cockpit to see if she can figure out what the problem is. This should be a fast instrument scan; her instruments will probably identify the problem fairly quickly. If she sees a simple cause for the failure, such as a fuel-switch buss trip for example, she can try to reset the system and attempt an engine restart. However, she doesn't want to spend much time on this process unless the engine(s) fire immediately. The safety of the aircraft is always a pilot's first job.
After the pilot has decided that the engine or engines aren't going to fire, he needs to get on the radio and tell someone on the ground what's going on. This condition is typically announced by calling out "Mayday," then delivering the aircraft number, stating the emergency and telling the ground controller where the pilot intends to land. The controller will review the information, alert emergency services and sometimes offer alternative landing sites if available. However, the pilot is the final decision-maker in this case.
At this point, it's time to secure the airplane for a forced landing. This means the cockpit crew should tidy the cockpit by stowing unnecessary books, manuals, pencils or other equipment that could start flying if the landing is rough. The pilot should pull down on his harnesses and fly the airplane to a controlled landing.