Your camera should still take the photo at the correct exposure , you will just have to be a little more careful of shake when using it .
It works best at an angle to the sun , but can work in any direction .
To work it -
1 - Focus on your subject
2 - turn polarizer until you get desired result , make sure you don't turn your focus , or else when you refocus , the polarizer will turn and you will not get the result you wanted (For lenses where the front ring turns at focus)
3 - The darker your image through the viewfinder , the more enhanced your polarizing effect will come out in your picture.
When it is turned so that things are brightest , it acts more like a neutral density , and you will have very little polarization effect.
Even though it looks dark in the viewfinder , it should come out properly exposed in your pic.
4 - The most important thing to note , is that the polarizer is great for using during the day , it is not really a tool to be used often in the early morning or late afternoon , as it hogs to much light , between 1 and 3 stops depending on the conditions.
1 - Use it for scenery pics , or pics of herds of animals where there are clouds and/or blue sky , use it to enhance the clouds , normally when you turn it till the sky looks darkest (This will also make the blue sky super blue) .The biggest thing to be careful of when doing this is that 1 side of your pictures sky is very dark , and the others is light.
2 - as for above , it can also be used to reduce the amount of contrast between the sky , and your ground subject making it easier not to wash out the sky in your pic , due to the skies brightness.
3 - use it when shooting at water . turn it until you remove the glare of the water surface , and it becomes see through .
This is fine for either wide angle or close ups in the water .
4 - always try take a few snaps at various levels of polarization , you can often get a great effect at half way between dark and not , especially when trying to get a bit of an animals reflection in the picture , or where there are slight ripples in the water.
5 - Use it to bring out nice green colours when taking snaps of something where there is lots of green grass
6 - It can help for general photos in bright conditions , or overcast but bright times , to reduce the haze.
7 - If it has been raining , and it clears up , you can get some splendid pics using it when the plants and grass are still wet.
8 - when taking snaps of birds on branches , where the sky is the background , it helps to use maximum polarization to darken the sky behind the bird and thereby getting a much better pic with a blue background ,rather than those whitewashed bird on branch snaps.
Ill try find some pics to illustrate a bit later.