I am totally addicted to Fair Isle now, but it scared me for the longest time. I took a class at my LYS and ended up in tears (along with another classmate). :rollseyes: We learned to do it two handed, with your normal knitting hand holding the main color and the other hand holding the accent color. For me, that was knitting the main color English and the accent color continental. UGH!!!! My left hand would never cooperate. It was horrendous, but after practice, it's soooooooooooo much fun. I actually have a much easier time with intarsia, but the results of Fair Isle are so much more rewarding!
Give a small project a try and see if you can find the best way to hold both strands of yarn. Once you are comfortable, go for the vest. It look beautiful!