One item it many photographers bag is a polarising filter and its surprising how many photographers don't know how to use them!
Let take a look at polarising filters.
So what does it do?
How to use it
Its important to know that polarizing filters work best when at a 90° angle from the sun. This means that you should practically never use a polarizer facing directly toward the sun. If the angle is wrong or the filter incorrectly set it can result in dark patches in the sky. Its a good idea to take off the filter for shots that include the sun as the extra glass can result in an increase in flaring. So, your sunsets and sunrise photos will be better off without the filter.
How to correct mistakes