Every man's fear. If you shoot before you see the whites of her eyes, make sure you have a backup plan to ensure her pleasure too. It may appear to you that humping for an hour without climaxing is the mark of a sex god, but to her it's more likely the mark of a numb vagina. At least buy some intriguing wall hangings, so she has something to hold her interest while you're playing Marathon Man. You really ought to be able to tell.
Most women make noise.
Don't act like a giant cat at a saucer of milk. Get your whole mouth down there, and concentrate on gently rotating or flicking your tongue on her clitoris. All women hate this. It's about three steps from being dragged to a cave by their hair. Sperm tastes like sea water mixed with egg white.