I've taught a few people. Taught a friend of mine a few years ago in a parking lot, then on some back roads. She did fine (a bit nervous) but actually chirped the tires shifting into second (I cringed).
The biggest mistake I ever made was letting one of my coworkers drive the car because she had never driven stick on a car before. Working for a bus company, we all drove 6spd buses. She was essentially double clutching my car (which is fine, because i do it all the time)... the problem is that she was putting the gas all the way down during every shift. I swear I felt like trying to reach over and turn off the car! I'm sure that is why my clutch is chirping on hill starts at only 88k miles.
