Suppose someone is going to be a counselor (in a camp) in the summer. What are some Halachos that specifically pertain to the job that he/she should review?
I'm thinking Lashon HaRa' and Hashavath Aveidah are probably among the two most prevalent sets of Halachoth that would require review. (Of course many other every day Halachoth would be relevant as well, but I'm considering those that might need to be refreshed.)
I would say all the Halochos of Bain Odom L'Chavairo.
If the camp has both male and female counselors and/or campers, the halachos of yichud and arayos would be important.
Not specific to counselors, really, but if you're in the countryside for the summer, you should be familiar with at least the basic rules of techumin and making an eruv techumin.