I think the important thing is don't overuse it. It can make your sky go dark in certain conditions. Remember that it will reduce the amount of light by a couple stops.
They also work best if the sun 90 degrees to your shooting direction (try to keep the sun in line with your shoulders).
If you see a shot with a lot of reflected light (ie. looking into a valley while the sun reflects off of leaves and roofs), go for it. Then take another shot without the filter--sort of like bracketing your shots.
You might find that the non-polarized shot works better.
Other than that, there isn't much to it.
Take lots of shots and have fun. We all want to see them when you get back.
