1. Not Knowing the Rules: This seems like a basic thing, but a host being unclear on the finer points of the game show rules can lead to a chaotic or less-than-ideal experience for the game show participants. This is especially true as you customize your game show and add multiple rounds with multipliers (i.e. points are doubled!) or rule variations.
2. Getting Down on Wrong Answers: Nothing is more discouraging than being in a learning game situation and being mocked or ridiculed (no matter how gently) for putting yourself out there and answering a question. Most trainers have a good sense of appropriate feedback, but sometimes an outside-the-training-department host won't have a similar taste for protocol.
3. Not Encouraging Teams: If a game is set up cleverly, there's always a chance for a team that is behind to catch up--be it in a wager round, bonus points, etc. However, it can be easy for a team to forget this when they see such a glaring disparity in scores. It's the host's job to remind the teams of the stakes and preview rounds where they may have a good chance to catch up.
