* Don't draw attention to your worst bits by trying to cover them up. For example, a woman who is big on top will only emphasise her size if she tries to conceal it with a long, round-necked, short-sleeved T-shirt. She should go for V-necks, buttons down the front, a three-quarter sleeve, and maybe a shirt with a tail to break up and lengthen her proportions. ("And there are," says Ms Bull, "hundreds of tricks that you can do like that.")
* Don't buy clothes in a rush. Instead of running around the shops, spend time at home, in front of the mirror, trying on what you've got in your wardrobe already and being ruthless in working out exactly what suits you, and why, before buying anything new.
* Don't buy the same thing over and over again. How many of us have cupboards full of black trousers? Or white blouses? Or blue shirts?
* Don't dress older than you are - a particular pitfall for women in their late thirties. "I say to them, 'Why not wear now what you might still be able to get into in 10 years' time, but you certainly won't be able to get away with then?" says Ms Bull.
* Pay more attention to fit. Fit is king.