Nothing puts a quicker end to working in the garage than frigid temperatures made worse by a lack of insulation. But before you think about plugging in a heater, try sealing the space against drafts. Replace the rubber gasket on the bottom of the garage door and put new weatherstripping around any other doors. While you're at it, fill gaps around garage windows with caulk. Sealing the garage will trap warm air, making for a more comfortable work space.