i get a no pull harness from wal mart. it has a thin strap that goes around the belly. when the dog pulls on the leash, the part around the belly contracts and the dog stops pulling.

downside - if you need to pull the dog towards you, unsnap from this and snap the leash to a regular collar. otherwise you can't control the dog.

i have also used the leash around my belly trick. i walk with a fanny pack. i hook the leash to the fanny pack. when the dog pulls hard he has to overcome my considerable weight in order to get anywhere.

downside - if you are walking on gravel, the dog can cause some slipping and sliding to make you fall. do not try this on gravel.

on the leash that reels into a case. i had one of these. this was good until the dog spotted some wildlife he wanted to chase, while i was locking the door. i saw him take off and i held hard to the leash. when he hit the end he broke the spring inside. even tho he is large and i bought the extra large size he still broke it.