You can have a hangover from other things than alcohol. I had one from women.

Love interest nearly always weakens a mystery because it introduces a type of suspense that is antagonistic to the detective's struggle to solve the problem. It stacks the cards, and in nine cases out of ten, it eliminates at least two useful suspects. The only effective love interest is that which creates a personal hazard for the detective - but which, at the same time, you instinctively feel to be a mere episode. A really good detective never gets married.

When the plot flags, bring in a man with a gun.

Neither of the two people in the room paid any attention to the way I came in, although only one of them was dead.

She lowered her lashes until they almost cuddled her cheeks and slowly raised them again, like a theatre curtain. I was to get to know that trick. That was supposed to make me roll over on my back with all four paws in the air.

The agent never receipts his bill, puts his hat on and bows himself out. He stays around forever, not only for as long as you can write anything that anyone will buy, but as long as anyone will buy any portion of any right to anything that you ever did write. He just takes ten per cent of your life.

The plants filled the place, a forest of them, with nasty meaty leaves and stalks like the newly washed fingers of dead men.