Watch the Carol online guitar lesson by Brooks Robertson from Fingerstyle Survival Guide
As I mentioned with some of the other etudes in section 2, it is important to approach learning any new song by dividing it up into bite-sized, approachable parts and working slowly on those parts one at a time. Once you have multiple different measures worked out and memorized you can start stitching them together. I remember Buster stressing to me when I was learning songs from him that although I wanted to quickly be able to play the songs at warp speed like he did, I would never achieve that unless I could play it very slowly and accurately first. It really is effective to start learning things slowly and after you really have it internalized begin speeding it up. This would be a great tune to practice while playing with a metronome.