Photography is a skill, as well as an accumulation of experience. Below are twelve of the most classic and practical photography techniques gathered from the experience of countless photographers. Memorizing them will help you handle many challenging shooting scenarios
Classic 12
1. Sunny 16 Rule (Sunny 16 Rule) The "Sunny 16 Rule" is a method for correctly estimating exposure values in daylight when you don’t have a light meter, so this rule is only suitable for use in bright sunlight. Set the aperture to F/16, and match the shutter speed to the ISO or slightly faster. For example, when the ISO is set to 100, the shutter speed should be 1/100 second (or 1/125 second). Therefore, according to this rule, when photographing on the beach, you should use an aperture of F/22, and on cloudy days, an aperture of F/11.

2. Moon 11, 8 and 5.6 Rule (Moony 11, 8 and 5.6 Rules) If you want to photograph the moon, here’s a good rule to follow. When the shutter speed is synchronized with the ISO, use an aperture of F11 for a full moon, F8 for a half moon, and F5.6 for a crescent moon.

3. Camera Shake Rule
       When shooting handheld, your shutter speed should not be slower than the reciprocal of your lens focal length. The slower the shutter speed, the more likely camera shake will reduce sharpness. For a 50mm focal length, the shutter speed should be at least 1/60 second—preferably 1/125 second. Only in extremely low light should you use a flash, tripod, or place the camera on a hard surface to prevent shake.

4. Gray Card Rule (Anatomical Gray Card)
18% Mid-gray Card
Carrying an 18% mid-gray card is a powerful tool for shooting. But what if you don’t have a gray card? You can face your palm toward the light, meter it, and then add one stop of exposure.

5. Depth of Field Rule (Depth of Field Rules)
       The background depth of field is twice that of the foreground depth of field.
       When the subject has significant depth, focus on the front third of the depth of field, because the depth behind the focus point will be twice as deep as in front. This rule applies to all combinations of apertures and focal lengths. Remember, the smaller the aperture and the shorter the focal length, and the farther the distance to the subject, the greater the depth of field.

6. Digital Print Size Rule (Largest Digital Print Rule)
   　If you want to print your work as large photos, the image size should not exceed the digital image’s pixel dimensions divided by 200. If you have high quality requirements, divide by at least 250.

7. Exposure Rule (Exposure Rules)
       When processing digital photos, the most common rule is to ensure accurate exposure in the highlights and let the shadows fall where they may. But when processing negative film, especially color negative film, it’s best to overexpose by one stop.

8. Quick Flash Fill Rule (Quick Flash-fill Rule)
       When your camera cannot automatically control the output of the flash, set the flash ISO to double the film’s ISO. If you meter the main subject, set the camera aperture to a full stop and match the flash to the same aperture. This way, the shadow areas of the photo will be one stop darker than the main subject.

9. Flash Range Rule (Flash Range Rule)
       This rule is simple: double the distance, quadruple the ISO. For example, if your flash has an effective range of 20 meters at ISO 100, to increase the range to 40 meters, you’ll need to raise the ISO to 400.

10. Pixel Doubling Rule (Megapixel Multiplier Rule)
If you want to double the resolution of your digital camera, simply quadruple the number of pixels.

11. Action Stopping Rule (Action-stopping Rule) This rule comes from an empirical formula of angles and speeds. If you can capture an object moving along the axis of the lens with a shutter speed of 1/125, then motion perpendicular to the lens axis can be captured with 1/500 second. That means, if the object moves at a 45-degree angle to the lens axis, a shutter speed of 1/250 is sufficient.

12. Sunset Rule (Sunset Rule)
When photographing a sunset, meter the top part of the sun, but do not let the sun appear in your viewfinder. If you want the sunset to look like it’s an hour later than it actually is, reduce the exposure compensation by 1.