I made a sample sandwich and tried several threads and needles. I prefer Perle size 8 or 12 or Aurifil 12. Sulky 12 wt. Is actually a bit thinner than I like, but I use it when it suits the quilt. I also tried several weights of crochet cotton. The size 10 is too difficult to quilt with, but the 20 and 30 wts are great. The only issue is that I only have white and ecru. My daughter and I plan to dye some when we get the chance. I use whatever color looks good on the quilt. Have fun experimenting!