Pay attention to where you are and see what is around you. If there is anything metallic around where you are trying to set up and take off from, you could get a compass error or a notice to calibrate your compass. Sometimes you don't even know that there is metal around, for instance a side walk could have some rebar in it, and that may cause an error. Compass recalibration each time you fly isn't a bad thing though, many people do it at the beginning of a series of flights at a single location, especially if you have traveled a long distance from your last flight.
