One of the most important things to teach a service dog, or any dog for that matter is how to walk politely on leash. Sometimes called 'loose leash walking', this habit is crucial. It prevents falls, and keeps your dog in reach if you need them, without pulling and forging.
These three videos are where I go to teach my pups how to walk nicely beside me. It takes a while to go through the technique, but in the end, you have a well behaved dog that sticks by your side, matching your every step.
Start with short sessions - this type of training can tire a dog out, especially when they're young. Five minutes is the maximum amount of time, per day, that they can retain information from.
Then go on to play with a flirt pole, throw a ball around, or just play tug. Going for a nap is good right after this kind of training. Then the information has time to sink in and be retained.