Keep it quiet for the tie in knot

This is a simple suggestion, but potentially a very important one: Avoid talking to someone when you, or they, are tying into the rope.

When anyone is tying what is potentially the most important knot of your/their life, it's best to give it your undivided attention.

Think of it as the equivalent of packing a parachute. If your friend was packing a parachute, you would hopefully not be distracting them with any sort of chatter, and hopefully they would do the same for you.