Medieval POC mentioned Janet Stephens on twitter recently and I've been watching her videos and reading the paper she did on ancient Roman hairdressing (link goes to a pdf of the article) and it's very interesting stuff. She also did an interview on The History Blog, where she explains how she, a trained hairdresser, got into doing recreations of ancient hairstyles.
It's cool to see someone do actual ancient hairstyles on modern people using ancient techniques and tools. It's also interesting - from a writing perspective - to consider how different hairstyles reflect the type of hair people in the past had in particular regions of the world (you can't put all hair up in the same styles - length, thickness, wave/curliness, etc. all factor in). A friend and I were discussing this and she pointed out that climate can play a role in hairstyles as well as humidity and temperature can affect hair (humidity can cause frizziness, for example). Similarly, the complexity of the style determines status: poor people dress their own hair while rich people have servants do theirs.