• TTL metering means Through The Lens or using the meter built into your camera. This is different than using a hand held meter because the hand held may not have any filters on it and you may be metering a different area than your composition through your camera.
• Many cameras have settings which restrict the meter readings to certain areas within the viewfinder. Matrix metering uses the entire area withing the viewfinder. Centerweighted uses an area in the center which is 20 to 30% of the distance across the viewfinder. Spot metering (the one I find most useful) measures the light at the center of the viewfinder and used about 5% of the area. This makes spot metering very selective.
• Incidence metering is done via a hand held meter with the capability of measuring ambient (light from all around the area) light. This might be useful for portrait and or flash photography.

The tips below relate to TTL metering:

1. Over expose white things by 1 and 1/2 to 2 stops to get the proper exposure on your film.
2. Underexpose dark things by 1 to 1 1/2 stops to get the proper exposure on the film.
3. Spot metering can be very effective if you can meter off of something in your image that is neutral toned or of a known brightness. For example, if there is something white which is in the same light as your subject, you can meter off the white thing , setting your exposure at 2 stops over, then take the picture after you recompose your main subject (but don't change the exposure or f/stop settings)

4. Also, you can meter off the palm of your hand and over expose by 1 stop.(provided your hand is in the same light as your subject).
5. If you have a neutral gray camera bag you can meter off of it provided it is in the same light as your subject.
6. You might also want to consider using a gray card for obtaining a neutral tone reading with your spot meter.
7. The Sunny 16 rule goes as follows, in the mid day sun, set the aperture on your camera to f/16, point your camera to the northern sky about 45 degrees above the horizon and meter this area. Your exposure should equal the film speed you have in your camera. (This won't work if you have polarizing or other exposure altering filters on your camera.) Anyway, you can use this not only to test your camera's meter but if you are out in the mid day sun, shooting at f/16 and your film speed is 50 but your meter suggests an exposure of 1/200th sec. then something is probably wrong with the way you are metering or you could be metering a very light colored object. Don't forget to compensate if you are shooting at a different f-stop than f/16 or if you have a polarizing filter on your lens..
8. Sometimes the light difference between the lightest and darkest parts of your image may exceed the 5 stops that slide film is able to record. You can test for this condition by spot metering the bright area and the dark area. If there are more than 5 stops between the two you might want to try a split neutral density filter to even out the amount of light reaching the film.