Thanks to Larene for this tip on Picot’s:
From Cyber~Stitch Newsletter by Susan Carlson

I'm just beginning to get more into Hardanger. But, I do think I figured out what works for me when I'm making picots. When I make the little thread circle, and before I pull the thread tight, I insert a size 26 tapestry needle into the hole, and keep in there until I've pulled the thread tight AND have needle woven back to the other side where the picot started. This makes the perfect size circle (I started with using a size 22 and then a 24 needle, and they were both a bit too large), and it also helps keep the circle on the "side" of the kloster block, instead of on top of it.

I would also highly recommend the book by Linda Driskell called Victorian Hardanger Sewing Accessories. The illustrations she provides for making picots were the easiest ones I've found to understand.