When you go to the Shampoodle hair salon in your Nookingtons store the poodle will ask you some questions while you are sat in the chair.
When she asks you wether you would like warm or cold colours, pick what you want and then you will be asked to look deep inside you and tell her what style you think your true hair is, this will determine your colour.
Her is an easy colour guide.
Warm:
Safe= light brown
Lighthearted= blonde
Fiery= red/ginger
Flirty= pink

Cold:
Mysterious= dark brown
Young= blue
Lush= green
Radiant= white

Hairstyles:
Hairstyles depend on what you choose, theres lots of options, which you will have to figure out yourself but I will give you 3 of the more popular hairstyles and some colour suggestions.

Long with a flick and a side part (looks good in pink):
Big Nights
Well,duh
Nah/power ballad

Bob with blunt fringe (looks good in blonde):
Every Day
Sweaty
Nah

Pig tails with zig-zag fringe (looks good in dark brown):
Big nights
unfortunately
I'd rather not.