I serve it really tight. I push and pull to make it so.
At the top , I give it a few half hitches.
Then, I tie the finishing knot for the serving.
Explaining that is hard.
Tim Baker did it it in one of the TBB's and I can find the reference if anyone is interested.
Only experienced and accomplished bowyers I do thank them, have been commenting recently so I am not sure if beginners have hung in there and the reference may not be needed.
Photo shows the finished serving.
Jawge