Here are some ideas to get you started: https://www.youtube.com/watch?v=lWrzcZRcd8Q
There are books and magazines on this very topic. Home improvement centers and proper newsstands carry them, I would buy a few and follow their suggestions - insulation will be key to keep you warm and toasty in winter and cooler in summer.
Hi Jenn! That sounds like a great project, and in addition to the above information hopefully these links will help you too! Merry Christmas!