I knew I wanted to crochet it, and I knew I had to choose a pattern that I wouldn't get bored with over the year. I also did the math and realized that this was going to be a very long scarf, even if I used SC (single crochet stitch) so I just went with HDC (half-double crochet) because I liked the look of it.
I used the Petals to Picots V-Stitch Afghan pattern,
but modified it to be HDC.
I chose Madelinetosh Tosh Merino Light because I'd worked with it before and LOVED it. You can also get samples and shorter skeins of it cheaper than buying an entire skein. (Most of the colors were Unicorn Tails from Jimmy Beans Wool or WEBS. I used an F hook. (3.75mm)