Insulation, Radiant and Vapor Barriers - Garage door insulation

I want to use my garage during the winter months as a workshop. I need some ideas on how best to insulate my two garage doors,each measuring 8' wide and 7' high constructed of masonite panels inside wood frames.

You can cut foam core board to fit the panels on the inside of your garage door. They come in 4x8 sheets. If panels can't be slipped into panels, these can be glued to the door panels. Take into consideration clearances as the door moves up and down. You will be changing the weight of the door, which will require adjustment to counter springs. Springs perpendicular to the door on pulleys with cables, you can DIY with door open. It is not recommend that you DIY if you have torsion spring above door on header. For safety, call a professional.

Garage door weatherstripping that fits along bottom of door is available at home centers and hardwares.

xero,
Most all garage doors are not made very energy efficient. Just check the side and bottom seals for severe leakage.
With the garage door closed to block wind, some type of heater(mine is kerosene) will heat it sufficiently w/o any added door insulation. I'm in VA and have similar temps to you.
Be careful with the dust and fumes with any type flame heater.

fred