Bree123 has great information for you. I forgot to mention that I currently use 2 strands of embroidery floss for the wool stitching. However, in the future I will be switching to Pearl Cotton probably #5 or thereabouts. I find that the floss sometimes it difficult to work with since it is two strands. I like the idea of only having to deal with one strand that will cover the drawn design line well but that may not matter to others. I think it might be nice to use wool threads also but I think that can get pricey. I cannot remember if you mentioned whether you already have a project in mind. Have you decided what you want to start on first?