Start with a piece of wire, I don't really measure I just went with my wingspan of my arms. Now I have long arms so I would say its over a yard stick. That is plenty of wire, but I always like to be safe. We want to cover the end wire, so I ran it parallel to the comb, we will do an initial wrap to lock it in place. Then as we go the remainder of the wire will be covered.
And just add beads. Now I forgot to mention to check that your wire will go through you beads. Again another reason to use a thin wire. I usually add a bead, wrap to lock the bead in the next groove, repeat.
So I stuck with thin, lighter beads. Here are all the combs I made.