* From day one, make the dog always stay on your left. Every time you walk, run, go anywhere, he should be on your left side and he should stay there. If he's crossing or weaving into your path, correct it immediately because if he does that when you're running, you're both going to get hurt. If the kids walk the dog, be sure they know he has to stay on the left.
* From day one, teach him "leave it." Don't let him sniff things, stray into the ditch, or cross your path to bark at a dog across the street. A firm "leave it!" and a snap on the choke, teaches them right away that when you're running, you're running -- you'll tolerate no messing around, chasing birds, or stopping to smell the roses -- unless you say so, of course.
* If you run in the dark, invest in a light-up collar and leash. This was important for me because Sammy is black. I paid big money for a light-up collar online, but now they sell them at Walmart.
* Dogs will run much longer than they should, so don't take your cue from the dog. He'd run for hours if I let him, but I know it's not good for him to go more than a few miles now.
* I would caution that it's not easy...and it will take time to get a dog who knows what he's supposed to do (never cross in front of you, stay on the left, leave a little slack in the leash). It's actually pretty exhausting to run with Sam because I get an upper body workout just keeping him in line. There are days I really just want to go run on my own, but...he sees me in running clothes & gives me those puppy dog eyes that I cannot resist.
* Use the collar that works for you/your dog. I use a choke when we run because he is virtually unmanageable without it. A running friend just told me that she uses a harness on her dog and puts it on backwards (with the buckle on the belly, so if the dog goes ahead, he's pulled right into her side. I haven't tried that yet. Some say choke collars are "cruel" and I should use a "gentle lead" (goes on their nose), but every dog trainer out there scoffs at gentle leads & says they provide zero control over a larger dog.
* As for leash length, I have a shorter leash (4 foot) and a longer one (6 foot), I prefer the longer one when we run alone on our country roads (not much traffic, etc.), but I used the shorter one when we go to the peninsula or another place where I need him to stay closer to me.
* Don't forget your doggie bag. Stinks (literally) to have to carry a bag of poop with you on your run, but it's rude to leave it behind ...and Sammy almost always has to poop after the first 1/4 or 1/2 mile. I've started running in one direction for a 1/4 or 1/2 mile, then we circle back and I drop the "package" off at my house as we continue on in the other direction.