So, my daughter wanted to dye her hair blue by her 12th birthday, after seeing some of her friends do the same with dramatic colors.

She chose the peekaboo hairstyle where the hair dye would only be applied to the lower layers of her hair. That way, the blue hair only showed a little at the ends from the front or back and would show more if she tied up her hair into a ponytail or did a half-up half-down hairdo. 

1. The appointment ran from 5pm to 7:30pm. It would actually take till 8 pm if I hadn’t hurried the hairdresser toward the end. The process involved bleaching the hair you want to be dyed and waiting for half hr or so till it turned a bit yellow/orange. The hairdresser then washed the bleached hair with blue shampoo so that the desired blue color can be achieved when coloring it. Finally, she then dyed the bleached hair blue. We had to wait a while before washing her hair a bit and them blow-drying the hair. 
2. The dyed hair needs to be fully dried before leaving the salon
3. The hairdresser warned to always wash hair with cold water to prevent the dye from fading or turning into grey or green shades.
4. She also said not to go swimming often, and to use an old towel or cloth on the pillow to avoid tainting the covers. My daughter is enrolled in swim classes, but luckily the dye stayed on after her first class. 
5. My daughter’s neck and the top of her shirts were pretty much blue for 1-2 weeks. It seemed to get a bit better after a week, but the blue tint was still there over her skin. She had to keep wiping it down every night and wash her clothes with an alcohol-based agent before tossing them into the laundry machine. Update – we realized later that she should have washed her hair on alternate days with the color treatment shampoo and that stopped the dye bleeding onto her skin and clothes. She avoided hair washing for a while thinking it would remove the hair dye completely.
6. Make sure you use shampoo for color-treated hair – professional ones like Bedhead, Redken, or Biolage were recommended by the hairdresser. Using regular shampoo may wash out the dye and you will regret spending over $100 to get your hair dyed.
7. Also, avoid getting your hair wet often…
8. Next time, highlights or ombre would be better so that the neck and clothes don’t get stained
9. My daughter didn’t wash her hair for around 2 weeks, and the hair dye bled all the time. After she did hair wash once in 2 days few times, the bleeding of hair dye reduced significantly.