The longer you want your twisted bead piece to be, the more beads you will obviously need. In fact, even if you make a shorter piece for a bracelet, this method requires lots and lots of beads because the spiral becomes very dense.
First you need to decide how many different sized beads you want to use. You can use as few as two on up to five or even more. The more you use, the thicker the twist, and the more involved the project. I have found that 4 to 5 different sized beads makes a nice size twist, but it is up to you. You want to use beads that are sized from 4mm (as the largest) to size 11 seed beads (as the smallest). Beads will be strung in graduated sizes as you work around to create the spiral.
As with all beadweaving projects, you will of course need either Nymo or Silamide thread and a beading needle. If you use Nymo, you will need to coat it with bees wax or Thread Heaven.