What could you try for the first time?

I was singing with the choir tonight and I noticed a friend had got her hair coloured very subtle purple shades. A bit like this free photo but on much shorter hair.

I have had a box of hair colour in the cupboard for a couple of years, but I keep chickening out on using it. I’m worried I might be allergic to the dye and also I have watched several videos and you can’t just use it like shampoo you have to put it in thin layers to spread it evenly over your hair. I don’t think I can physically do that!

I once asked a hairdresser to do it but she would not use a dye by a different supplier as it was a problem if it went wrong. Shall I just try and shampoo it in or give up and throw it away? I have become very risk averse!