Electric drills are very useful. They can be used to make holes for doors, or to guide a nail or screw to protect wood from stripping. They can be affixed with a screwdriver bit, or a buffer brush to make quick repairs. To ensure that your electric drill will do what you need it to do, it's important to perform occasional maintenance on it.
Machine oil can be used to improve the moving parts of your electric drill. Be careful to just put a drop or two into the mechanism so that you don't over-lubricate. Doing that will not help your motor, as it will cause the gears to slip.
Dust can collect in the moving parts of electric drills. If you find that the moving parts are not moving as well, if your drill seems to be over-heating or if you actually see dust collecting in the moving parts, you can use an aerosol cleanser designed for electric components. Using compressed air may clear the dust, but if it's collecting on oil you may choose an acetone-based aerosol instead. The latter will help cut through the gummed up dust. Be sure to use a machine oil lubricant when you've finished cleaning to re-lubricate the motor.