I finally caved and started throwing on a hairnut for schooling. I have layers, so I have a lot of short hair that doesn't tightly fit into a low ponytail. The hairnet keeps the short hairs from sliding down and popping out of the sides of my helmet and it also make its easier to keep my bangs under the helmet. The only way I could get the same result without a net is if I gelled my hair back... which would 1. be gross after sweating (and I am quite the head sweater) and 2. mess up the inside of my helmet.
My helmet is sized to fit perfectly with my ponytail underneath it, so a French braid or anything along those lines won't work.