When I worked as a Saturday girl in a department store, I learned the saying from the girls in the millinery department "Red hat, no drawers". I think the thing about "fur coat, no drawers" is more sinister.
Being a working girl still, I have to dress fairly reasonably most days. I always wear a pair of plain trousers, a top, and a jacket, blazer, or something loose over the top to disguise my "spare tyres". Patterns and prints I avoid at all costs - especially next to my face - and I don't possess any jewellery - can't bear the thought of metal on my skin.
Today's colour spectrum is black (trousers) , olive (sleeveless top) and natural linen (I won't say beige!). The last is actually patterned, but very discreetly with tone-in-tone, off-white and fawn. I bought it to support a friend who ran a shop selling clothes in natural fibres.
Another favourite colour spectrum is pinks, mauves and puces, or a mixture of light and royal blues. In the winter a variety of browns.