The first thing to consider when you’re colouring your hair is your lifestyle: are you high or low maintenance? Consider your makeup routine and clothing. Going any type of blonde if you’re a natural brunette is high maintenance. If you go to the salon say every three to six months, then do something that will have an easy grow out, such as highlights or lighter ends. If you have 40% or less grey then try a semi-permanent dye. It fades away and then you can retouch as you wish.

Don’t highlight your whole head. When you study, you don’t highlight the whole book. If you have curly hair, have a slightly thicker highlight, so it is powerful enough to see but not chunky. Most people look better with warm tones such as honey, caramel and toffee, which are more neutral. Usually ash tones are dull so don’t really work with many skin tones.

Going darker is easier: use a semi-permanent dye as a trial run. The best way to go lighter is to do it slowly. Add some highlights, then some more. That way you can see when a certain shade is light enough. If you colour your hair at home, be realistic and go for something simple. If you think it’s going to look as if you just stepped out of the salon, it’s not going to happen. Never bleach your hair out at home. You need someone who is skilled because bleach is a very strong chemical. You want to be afraid of that.

Rita Hazan, a celebrity colourist, who has worked with Beyoncé, Jennifer Lopez and Katy Perry, was talking to Amy Sedghi