Strobe lights are great for night signaling, but avoid looking at the flash. if you have been watching the strobe flash, you will not be able to see if you've been seen or not. Blindness from the strobe, while only temporary, will hinder and slow down the rescue. Turn your head away from the flashing light and glance at the sound of the aircraft every few seconds. Strobe lights can been seen in clear weather for long distances and while they work in poor weather, such as rain or fog, they're not as visible.
Signal mirrors are great for all environments, but are limited to only day use. Practice using your mirror before you need it! Once you get the attention of an aircraft, move the flash to the rear of the plane to avoid blinding the pilot, not to mention making him/her angry. If the aircraft appears to move away from your position, flash the mirror at the cockpit once or twice. Keep in mind, the aircraft that finds you may not be the aircraft that does the actual rescue. However, your position will be marked and rescue will come, but perhaps from the ground or air. Keep an open mind and be ready no matter where rescue comes from because you may only get one chance. Bad weather can easily stop a rescue and recover effort, but stay where you know they saw you, if the weather allows you to do so.
You can signal from the ground by stacking rocks, piling snow or brush. An "X" means you are unable to proceed and need assistance. Make your ground signals large enough to be seen from the air and that usually means about 3 or 4 feet wide and maybe 15 to 20 feet long. Make it high enough it casts a good shadow in the sunlight. Or, three fires burning in a triangle, three gunshots, or three loud blasts of a whistle. The key to remember, it three of anything. One of your fires can be your normal campfire, with the other two ready to light when you hear rescuers nearing. That means you'll need something to transport the fire from your campfire to the other two fires. You can use a piece of burning wood, but avoid dropping burning embers on the ground, it could cause a fire you don't want.