Treats that are small enough to give often enough.
When I first came home I wasn't very food motivated because everything else excited me: the smell of trees, sidewalks, all the shops we walked by, and especially other dogs, so Mom and Dad weren't sure how I would do off-leash. To make sure I would come back they used to buy me chicken nuggets from McDonalds. YUMMY!
They didn't want to feed me that every time, though, I wouldn't have minded it one bit, so Mom went a local boutique pet shop to find some healthier alternatives.
I'm a huge fan of the Real Meats Treats!
There are lots of different flavors but I like beef the best, so far. Mom gave these to another friend's puppy once and he almost followed us all the way home!
These are more expensive (in retail), but Mom likes that she can tear these up in half and use them as treats when we go running or for training, in general.
At Pawtrero, these are $7.50 for 4 oz, or $20.41 for 12oz. I have to admit, I go through the 4 oz bag pretty fast. The 12 oz bag can last me about a month if Mom rations, so Mom only gets these once in a while and alternates with the treats she buys at Costco.
She may just end up buying these on Amazon instead. If you're a prime member you can find some 12 oz flavors for a little under $14.
I still prefer human food but if you're going to use doggy treats, these are the way to go!