I was recently asked to teach some baby tracking to a few and since then asked to do a post on beginning tracking, and while I readily acknowledge that I am not a tracking expert, I can tell you how I'm teaching baby tracks now.
Note that I am teaching footstep tracking, in which the dog is expected to point out each step the human took. SAR dogs generally trail rather than track, meaning they follow the scent to its source and may take a completely different route than the original track, either shortcutting or following where the scent drifted downwind. AKC tracking, with its generous allowance of ranging widely off the track, is more accurately trailing.
First, I don't use the yard which we trample daily. The scent there is just too hot to expect a novice dog to distinguish. I use fields of relatively short grass, or I'd use soft dirt if I had that available (but my crop fields are all chemically treated by the farmer who rents them, so we don't use those). Big grassy fields, large little-used lawns, etc., are all options. Check out parks or local businesses (I got permission to track at a local car lot with a large front lawn that's purely for show).
It's probably best to start with a puppy square, which is essentially a 3'x3' area (larger for bigger dogs) pounded flat and seeded liberally with kibble or tiny treats. I use kibble in tracking, while most of the people I know use hot dogs or equivalent. I'm not personally comfortable with hot dogs as a food item :-) and also I want the dog to be following something less stinky than hot dogs. As long as she's motivated by the food, it'll work.
Stick a flag (like those the gas company marks lines with) at the bottom left corner of the square, stomp it all flat, let it age about ten or fifteen minutes and then let the dog work in it to find the good stuff. The lesson here is, put your nose down when you see a flag, and follow the scents of human/disturbed earth/crushed vegetation. See Armin Winkler's article for more.
Next, I'll start laying short baby tracks, maybe 10-20 steps. Flag at the start (get your nose down!) and a kibble in each step. I like to put a big pile of kibble at the end, but I'm ending that for Laev, who doesn't need any more encouragement to hurry. I'm about six inches from the dog, pointing to the track to start and praising quietly as she works, helping if necessary but generally trying to stay out of the way. If she gets off the track, I'll give her a couple seconds to put herself back on, as I don't want to teach helplessness; no more, though, because I don't want her to get distracted and reinforced by something else.
Corners and curves are introduced carefully, with me making sure that the dog won't be confused by blowing crosswinds. I do both directions (some dogs are naturally better at one than another), both obtuse and acute. I bait every step at a turn and then, later, I'll move the food to after the turn to reward an accurate track.
The most important thing is, I always have to know where the track is. I can't let the dog get off the track and be reinforced elsewhere or feel she's failed and doesn't know what to do. I have to be able to find the track no matter what. This is where the judicious use of flags, natural markers, sight lines, etc. all help!
Gradually I'll lengthen the tracks, fade the food, age the tracks longer, etc. It was suggested to me that if I use one piece of food in a footstep, I should use at least three in sequential steps, to keep the dog from developing the habit of finding one piece and then skipping ahead instead of continuing to check each step. Eventually I'll work myself back to the end of a 33' tracking line, but that's a long way away!
Okay, that may be the shortest tracking dissertation ever, but as I said, I don't consider myself good enough to teach, and there's a lot of better information online. Shakespeare's a pretty lousy tracker, but that's entirely my fault -- I started teaching trailing instead of footstep tracking, for use in a different venue, and then I was very inconsistent with practice while I tried to work out priorities. Consequently I have a lot of training band-aids to apply and fixes to accomplish. I've been much better with Laev, and I hope to continue in that vein!