Laser rangefinders can take the guesswork out of shot distances, but rapidly approaching game won't always leave you enough time for a reading. To be prepared, assess the range of several prominent landmarks (trees, brush, a trail intersection) as soon as you climb into your stand or blind. This way, you will have a mental map of distances and won't need to pick up the rangefinder if an animal is coming in fast. Use your device as a learning tool, too. I like to estimate how far away objects are from me as I walk and scout, then check my accuracy with the rangefinder. This skill is especially important when you're hunting open terrain, where handy reference points are typically hard to come by.