I would actually suggest sewing over gluing. Once you glue something on, it's gonna be hard to get off since it might rip some of the foam off with it. If you sew, you can simply pull the thread out and start again.
Don't worry, you'll get there. I was terrible at sewing when I made my fursuit head, but you can start on the back of the head so if you mess up too badly then it wont be very visible.
Just my opinion, find what works out for you best.