Copied from the main page:

• Introduce the Ko rule before it comes up in real play. It's a strange rule that is only interesting because of its consequences, which newbies are too inexperienced to understand fully. Talk about threats and fights and Ing rules and SuperKo, and the game's simplicity suddenly is gone. +
  • unkx80: I disagree with this statement, because the ko rule is one of the fundamental rules of go. I will introduce the ko rule, simply saying if there is no such rule, and both players do not give up the ko, then the game will never end. However, I will not go into the nitty gritty details of superko.
    • jfc: I agree with the original statement ^[1]. I when teaching in person I wait for a ko position to arise and then I let us go through the recycle capture a few times (sometimes I need to steer them into the repetitious cycle). Then I explain the absolute minimum of the simple ko rule.
      • symplicity: Usually, I will state something like "There is one more rule, which says that the whole-board position cannot be repeated" and leave it at that. I don't go into further detail unless the beginner wants to know more specifics (infrequent), or a ko position actually arises in play. It feels more elegant to lay all the rules up front, yet this method still keeps things simple.

[1] That is to say, the negative of the original statement, since the main page is a parody. (Clarification by xela, please correct me if I've read this wrongly.)