Start with the foundations: rewarding the dog intensively for being near you when you walk. Teach her what you want him to do. Start inside with no distractions. Then work up to larger distractions inside, then move outside to the yard, and only then try a walk. Use wonderful treats and use a lot of them. For 3 days, the dog gets all his kibble as treats during this game. Every single kibble!
a. start in your living room without a leash. Play with your dog for a moment to get him interested, then walk away, and c/t when your dog follows you. Turn and walk in another direction, c/t for following you. Do this 10 times (quickly--it's a game).
b. then raise your criteria: only c/t when he's within 6 feet of your left side. Do this for a minute (I set a timer which keeps me from cheating), offering at least 10-15 c/t during that minute. Then stop and call him over for a sit. Then start again. Repeat the minute-long game 5 times quickly.
c. then take a break, and later that day, do it again. Vary your speed a bit and do lots of turns, c/t whenever your dog is close to your left leg. Do this for one minute intervals, with a brief break in between each time, and repeat 5 times. Keep the reinforcement rate very high.
d. then put on the leash, and repeat. C/t at least 15 times in a minute, repeat 5 times. Your dog should be merrily chasing you around the living room. You are the Treat Machine and your dog is playing the world's best game: making the Treat Machine dispense.
2. BORING YARD as DISTRACTION
Now go outside in a fenced, boring yard, then start the game over from a through d, this time with the minor distractions of the yard.
Then go back indoors, and add a friend (or spouse) trying to distract the dog while you are practicing. Increase the distractions one at a time, with tossed balls, squeaky toys, etc.
Then move outside to your boring back yard, adding in distractions. Make the game fast, merry, rewarding, fun.
3. A REAL LIVE WALK!
Now it's time to try a walk down the street. Give him lots of aerobic exercise in the yard before you head out for practice walks, of course, since you won't actually be going far--maybe 100 yards, if that.
Practice for a moment inside, then in the yard, then move onto a boring road. Keep your rate of reinforcement very high--you might be shoveling treats into his mouth.
Pick a leash length you want him to stick to (I use 6 ft), and C/t BEFORE he reaches the end of that length. Vary your direction, run around a bit, make this FUN. Set him up for success, keeping distractions at a minimum, using tons of treats.
He should NEVER have a chance to get to the end of the leash in this first set of walks. Rinse, lather, repeat. A lot.
Keep a written record. It helps.
4. ADDING A CUE:
Then I add a cue word--I use the word "easy," meaning "walk with me on a loose leash." Some people don't like to use cues for LLW, because they want loose leash to be the default behavior, but I'm more comfortable with a cue.
Repeat using lots of c/t.
5. PENALTY YARDS GAME
After 3 days, with ALL the kibble coming from this wonderful game, your dog may now be ready for the Penalty Yards game. The beauty of the game is that it allows you to add powerful distractions in a controlled manner, once you have a strong set of foundations.
To start the game, move into a low distractions outdoor setting. Place a Truly Wonderful Thing your dog desires intensely (i.e., a huge pile of stinky treats), and put it in an obvious place, say on your quiet driveway. Let your dog watch you place it there, and let him get a good sniff of whatever you've set down there. Make sure he really knows it's there, and make sure he really wants what's there. (I use the Manners Minder, now my dog's favorite thing on earth, especially when it beeps telling him that food has been dispensed.)
Then run cheerfully (with several yummy treats in your hand) with your leashed dog to about 20 feet away, where your dog can see the Wonderful Thing. Make sure this starting point is obvious to both of you--I mark it by placing a jacket there, since we'll be running back there a lot at first.
Then give your LLW cue and start walking quickly toward the Wonderful Thing. The instant the leash goes taut, back up quickly all the way back to the starting point. (I cheerfully say "oops! Back to the beginning!" but it's probably best to do this silently).
Then cheerfully say your LLW cue again and walk quickly back to the Wonderful Thing. Move forward quickly when his leash is loose, and instantly reverse direction and zip back to the beginning the instant the leash goes taut. Make it snappy.
When your dog finally makes it to the Wonderful Thing, throw a party. Jackpot! Let him devour his wonderful thing, and then give more treats. Then run back to the start point and repeat 3 times.
It took my dog 3 very frustrating attempts to get at his Wonderful Thing until he finally reached it. But when he got it, he really understood.
After a break, repeat, and begin the play the Penalty Yards game in different, more distracting places. Make sure the Wonderful Thing is truly wonderful for your dog, something he desperately wants to reach. The more alluring it is, the faster he'll figure out that LLW gets him what he wants.
Good luck! The lesson from my experience is: work on the foundations first; increase criteria slowly; use great reinforcements at a high rate; and add distractions in an orderly fashion. And keep records. And practice, a lot, in new environments with new distractions. (Yes, I know, that should
all go without saying.)