This is a neat device. Some things that may assist you are:1.) first test it with distilled water and adjust accordingly via the circular piece on the bottom. You can use a flat head or your finger. Note, the entire plastic movable flap must be covered in liquid to produce an accurate reading.2.) refractometers should be used to measure the sugars in the mash and after the boil. Note, this device measures accurately at 20 Celsius (68 Fahrenheit) so if you take a reading below or higher than 20 Celsius then search for a refractometer correction chart in Google to aid in adjusting for the temperature difference.3.) this refractometer is not designed to read final gravity due to alcohol being more dense which makes the final gravity appear lower. I've heard of some that do read alcohol but some people say they are not accurate (off by 10% abv or so). The cheapest and sure way is to have a hydrometer and a hydrometer jar to measure the final gravity. Use the refractometer for everything else because it's faster and waste less wort.4.) this refractometer is designed to be used with natural light so the better the light, the clearer the lines of your reading.