Remember the challenge of changing your look as a model. It is very hard to change your look as a model and keep your marketing material updated.
many new models make the mistake of getting a makeover or by hair modeling in a hair show and get a totally un-marketable look afterward.
I have had good hair modeling experiences and bad ones. I like print ads are a better choice than a hair show, but a hair show could also offer you experience as a new model, but make sure you understand you have to keep your look commercial and sellable as a shorter model, not fashion sleek with a overly fashionable hair cut in the end.
Hair modeling can mean total drastic changes and you have to be able to handle it, not just emotionally either. Photo-wise. I remember i had just gotten new photos taken, headshots, and then I did hair show and had a totally different hair cut. You have to be able to market yourself as best as possible to agents, and then when you have an agent you have to be able to keep your photos updated and also looking like how you really like in real life. You can't show a long hair photo and then show up with short hair. It usually doesn't turn out good.
Also when it comes to color. You want a solid hair color. Not blond highlights. When an agent or agency as a client call they ask for a brown hair model, a brunette, a blond, not a girl with highlights typically. So pick a solid color. Black, Red, Brown, brunette...but not mixed highlights. You will book more work being able to be sent on a broad amount of castings, and you don't want your hair to mess up your chances.