The most important thing that you make sure that you do to ensure that you get an accurate reading to ti place the unit out in the open so that it achieves room temperature. This is especially important if you store it in a cool dark place that isn’t the same temperature as your home. Typically it just needs to be left on the bathroom counter for about 30 minutes before it is ready to be used. For using the probe in eardrums. You need to ensure that you pull down on the rigid point on the ear to allow for a straight shot near the eardrum where the probe is gathering information. Forehead models can be a little finicky, so you need to ensure that you touch all parts of the forehead running from one side to the other.