Colour blocking is simple and stylish, and a perfect fail safe if you have nothing to wear. This Topshop dress, £46, is good for those colour-blocking first-timers. These colours aren't too bright, and are suitable for nights out with the girls. Team with heels to match, or if you're feeling adventurous, try adding another colour. But no more than three colours at one time, otherwise you'll look like a rainbow!