Tracking is so much fun!!! It is Amazing to see what your dog can do!! My biggest "aww" moment with Riley was him tracking an hour old track in the Pouring rain on Pavement!!!
I agree with FP that you want to start him out with destractions. You want to introduce turns (start with open turns- like 120 degree turns instead of 90 degree turns), crosstracks, other dog smells, other people smells, different weather conditions, different surfaces, etc!! Also, if you are tracking on your own, every once in awhile have someone/some people follow you guys. Some dogs get destracted or actually really stress about someone talking and following.
We started tracking in a heavily used park. Lots of people, dogs, and wild animals use this area daily. Riley was fine and hasnt known any different. Also, like FP said, you will begin to tell when your dog is actually tracking or just messing around. A "get back to work" gets Riley quickly "on track" again!