You can talk to a man with a wooden leg, but you can't talk to one with a wooden head.
If you can't P155 up tall trees don't try running with the big dogs.
Those who don't do their paperwork properly end up with a dirty @rse.
Words of wisdom from an old boss of mine.
My favourite ones are are "you get what you pay for", "beggars can't be choosers" and "worrying is like sitting in a rocking chair, it keeps you busy but it doesn't get you anywhere".