Tracking is done on a tracking line, so you don't have to worry about the dog being off-leash. In fact, I start my beginners on a 6 ft. leash and buckle collar. When they have a good understanding of the basic idea, I move to a harness and longer tracking line.
Teaching is pretty straightforward. I use food--good smelly stuff like hotdogs, cheese, or liver treats. I rub a bit on the toes of my shoes, take baby steps and put a little piece of food down every step or two to start. You want to lay your starter tracks in short, straight lines or very gentle curves to begin with, and they don't need to be more than 20-50 steps long. At the end of the track, you want to lay an article (glove, sock, etc.,) and put food in it, on top of it, and underneath it. Finding this article is the goal. Put a marker, like a sprinkler flag at the start of the track and at the end, and as your tracks get longer, put a flag or two along the track, so you'll know where it is. Also when you return to the dog, arc around and give the fresh track a wide berth; don't cross over it.
You'll need to figure out what to do with the dog while you lay her tracks; consider leaving her in the car or having someone hold her. Having someone hold her near the start works well to get her revved up.
As the dog progresses, tracks get longer, turns are introduced, age and more turns are added. The food also gets faded.
Here are some excellent articles by Craig Greene, longtime basset owner and tracking judge.
Craig Green's Tracking Articles
Here are some other references that are usually available through vendors like Dogwise or 4-M Dog Books
Tracking from the Ground Up, Sandy Ganz and Sue Boyd (another Basset person and tracking judge)
Enthusiastic Tracking: The Step-by-Step Training Handbook, Sil Saunders
Bring Your Nose Over Here, Wentworth Brown--hard to find, but worth the effort. Various obedience and tracking clubs have copies for sale.
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