Here is my first string of onions. This is the section of the white onion harvest that had tops long enough to use. There are a handful of other onions which I put in a mesh bag. I didn't braid the tops of the onions, rather I used a method from John Seymour's "The New Self-Sufficient Gardener." He recommends tying together the ends of a 3 foot string to make a loop. Then you hang the loop from the hook. You have two parallel strings. You tie the first onion on the bottom of the loop and weave the tops back and forth between the strings. For the following onions, you don't have to tie, instead you just weave the tops in and out between the strings. Move the onions around the string to start in different places so the onions are evenly distributed around. I didn't end up using the whole length of the string for these white onions, so I knotted it off at the top and made a loop to hang it from.
Now I need to go practice some more on my yellow onions. There are many more yellow onions than white. Maybe I'll add photos to the steps above after I do my next string.