Using the DeWalt DCF850B is easy. First, make sure the battery is fully charged and properly inserted. Then, select the appropriate speed using the variable 3 - speed trigger based on your task. For driving large - diameter screws, a higher speed might be needed. When working in tight spaces, take advantage of its compact size. Always wear safety goggles and other appropriate safety gear. As for maintenance, keep the tool clean after each use. Wipe off any dust or debris. Check the battery regularly for signs of damage. If the tool isn't working properly, stop using it and have it checked by a professional. Store the tool in a dry place to prevent rust and damage.