Open a window at the top to let out smoke, and open a window at the bottom to breathe fresh air and signal for rescue. Do not open a window if smoke is rising from a lower floor. The smoke will just enter and fill the room that you are in. Stay close to the ground if there is heavy smoke. The air is usually less smoky near the floor.
Smoke is a killer.
More people die in fires from smoke inhalation than flames. Do not open doors that feel hot. Find another way out. A hot door means that there is fire behind it. Never use an elevator.