This will be presumptuous, especially for a newcomer here, but I couldn't help but sympathize with Bill in his desire for a brief, useful introduction to shooting "manual,:" so I thought I'd try writing one. It is below. It goes without saying that I shall be deeply grateful for any corrections and/or additions all the talent here may have:

How to shoot on “manual:”

1. Light comes in packets called “photons.” The more photons that fall on a camera’s sensor, the brighter the image is. If too few photons fall on the sensor, the image is too dark, and we say it is “underexposed.” If too many photons fall on the sensor, the image is too light, and we say it is “overexposed.”

2. When you double the number of photons falling on a camera’s sensor, we say you have increased the exposure by one stop. When you halve the number of photons falling on the sensor, we say you have decreased the exposure by one stop. A one stop change in exposure makes a noticeable difference in the brightness of the image, but it does not double or halve the brightness. Indeed, you usually have a usable image if your exposure is within one stop of the optimum.

3. The sensitivity of the sensor in a camera is governed by the “ISO” setting. Setting the ISO for a low number means it will take more light (more photons) to produce a usable image; setting it for a high number means it will take less light to produce that image. Very high ISO settings, however, are prone to produce noise, so should be avoided unless there is a compelling reason to us them. For most everyday photography, an ISO setting of 200 should be adequate.

4. Once the ISO of the sensor is established, the camera has two controls that determine the brightness of the image: aperture and shutter speed. When you shoot on “P” the camera’s computer adjusts both of these controls to yield a usable image. When you shoot on “M” you adjust the controls manually. When is it to your advantage to do so? There are many circumstances when “M” is best, but perhaps the most common are these: a) your subject is moving rapidly and you need a fast shutter speed to “stop” it, and b) you want to control the “depth of field” (the zone of sharp focus) in your image, and you do this by adjusting the aperture: a large opening (low f-number) produces a shallow field of sharp focus; a small opening (high f-number) produces a deep field of sharp focus.

5. In practice, then, when shooting in the “M” mode, having chosen the ISO you might then choose a trial shutter speed and aperture (f-number) and check the exposure. If the exposure is too low, you can increase it either by reducing the shutter speed or increasing the aperture (by selecting a lower f-number). You continue making these adjustments until your exposure meter tells you you have a suitable exposure. In adjusting shutter speed and aperture, NOTE THAT halving the shutter speed increases exposure by one stop, and doubling the shutter speed decreases exposure by one stop. Similarly with aperture: exposure decreases by one stop when you decrease aperture from f1.0 to f1.4 and from there to f2.0, then f2.8, then f4.0, then f5.6 then f8.0, then f11.0, then f16.0, then f22.0, and then f32.0 (see https://binged.it/2DwwSJ3).

When it's not sunny, you don't use the sunny 16 rule. You use the cloudy 8 rule. And when the sun is setting, then you use the sunny 4 rule......

Just remember to all you guys when you use your camera's meter to set the exposure: that if you want to rely on the camera's reflective meter, it is or may be off by at least ½ stop and maybe 1 full stop from the correct exposure provided from an incident meter. Note in an earlier post that the OP said he set his aperture at f/16, his ISO for 100, and then adjusted his shutter until the meter zero'ed out, giving him a shutter speed of 1/60.....well his shutter should have been set to 1/100, but with the reflective meter, it overexposed by ⅔ stop. This is what happens when you don't use an incident meter or fully engage the sunny 16 reciprocal settings.