I've read some books on AKC tracking, but I haven't employed them yet, because it is geared at tracking people, whereas I want my dog to track game. But one of the things the books unanimously advise is to use a long lead (~30 feet) with a tracking harness instead of a collar (a harness that doesn't restrict over the shoulders or at the neck). The idea is for the dog to pull you along the track, which they can do comfortably in a harness. As mentioned above, it also signals to the dog that it is time to work; we're not just out for a stroll.