Originally posted by voles Ok - what is the 'sunny 16' rule? I'm new around here.
Okay, so here's the basic principle: direct sunlight never changes in intensity. The sun is always the same brightness at any time of the day, on any day of the year (except sunrise and sunset). Remember that one stop of exposure is a doubling or halving of light, and common sense is enough to tell us that the sun never doubles or halves in power. If it ever did, we'd have much more important things than photographic exposure to worry about - such as surviving an extinction level catastrophe.
This means that for any camera there will be a "Sunny 16" exposure that will always be correct in direct sunlight. The classic rule is to match the shutter speed to the ISO and use f/16, so 1/125 at ISO 100 at f/16 is a good place to start.
An easy way to establish the Sunny 16 exposure for your camera in your part of the world is to take some test shots on a nice sunny day with some fluffy white clouds in the sky. Set up on a tripod with the sun out of the frame, but with the brightest highlights of the clouds easy to see. Start at f/22 at 1/125 at ISO 100 and then take a series of shots opening the aperture by a half or a third of a stop each time. You only need to go as far as f/8. And shoot raw files.
Now look at the raw files on your computer. completely unprocessed, and look for the frame where detail is still just visible in the brightest parts of the clouds. That's Sunny 16 for your sensor at your latitude. For me it's f/11 at 1/125 at ISO 100, or any reciprocal of that. f/8 at 1/250 or f/5.6 at 1/500 are exactly the same amount of exposure. Using this baseline exposure guarantees that I will always get the clouds right on the very edge of blowing out to white at the edges, which is exactly where I want them.
So now that you know where you're starting from with Sunny 16, you can use it as the basis for exposures in other light too. This is turning into a long post, so I won't go into detail about the adjustments for cloudy light as there are plenty of websites that explain it.
As Steve (Wtlwdwgn) says above, starting with Sunny 16 and checking the histogram on the playback screen is a great method to work with. It's about using your own eyes as your main exposure meter, with the camera's meter as an aid rather than a master. This is really only scratching the surface, but I hope it helps as a starter.