I've just had my hair coloured a medium brown with a hint of red which I really love. How do I keep the colour from fading? Should I use a shampoo specifically for brunettes or one for coloured hair and which is the best high street brand to go for? If I used a shampoo for red hair would that accentuate the red? Went into Super drug today but came out empty handed as there were so many to choose from!